In the molecule, the hydroxyl substituent is bound intramolecularly to the aldehyde group at the ortho position.Wavy layers of molecules are formed in the crystal structure of 5-methylsalicylaldehyde due to weak C—H⋯O interactions between methyl groups and the aromatic ring system. Molecules form columns in which the methyl groups are oriented in opposite directions layer-by-layer along cell axis  5-MSA; systematic name 2-hydroxy-5-methylbenzaldehyde), C8H8O2, was discovered to be a textbook example of the drastic structural changes caused by just a few weak C—H⋯O interactions due to the additional methylation of the aromatic ring compared to salicylaldehyde SA. This weak intermolecular hydrogen bonding is observed between aromatic or methyl carbon donor atoms and hydroxyl or aldehyde acceptor oxygen atoms with d(D⋯A) = 3.4801 (18) and 3.499 (11) Å. The molecule shows a distorted geometry of the aromatic ring with elongated bonds in the vicinity of substituted aldehyde and hydroxyl carbon atoms. The methyl hydrogen atoms are disordered over two sets of sites with occupancies of 0.69 (2) and 0.31 (2).The crystal structure of 5-methylsalicylaldehyde ( Its crystal structure is reported herein and compared to the unsubstituted form of salicylaldehyde (SA)  apart from van der Waals interactions. Three C—H⋯O interactions are present between either aromatic or methyl C atoms and aldehyde or alcohol oxygen atoms: two close to 3.5 Å with C10⋯O8 = 3.499 (2) Å and C5⋯O8 = 3.4801 (18) Å and corresponding C—H⋯O angles of 152 and 149.3 (13)°, respectively. The third and shortest interaction, has a C6⋯O9 distance of 3.4053 (18) Å and an angle of 138.7 (12)°  = 3.7539 (11) and 4.7456 (13) Å, respectively. This results in a deviation from the usually expected herringbone or completely planar arrangement of planar molecules. Wavy layers of molecules are formed instead, whereby the 5-MSA molecules form columns in which the methyl groups are oriented in opposite directions layer-by-layer along the a axis  at positions H10A, H10B, H10C and 0.31 (2) at positions H10D, H10E, H10F. They were included at idealized positions riding on the parent carbon atom, with isotropic displacement parameters iUso(H) = 1.5Ueq(CH3). Refinement of the corresponding site-occupation factors of the methyl-group hydrogen atoms was carried out using a free variable so that their sum is unity. All other hydrogen atoms were located individually in a difference-Fourier map and refined isotropically.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989017000238/lh5831sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989017000238/lh5831Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017000238/lh5831Isup3.cmlSupporting information file. DOI: 1525796CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The molecule has an {Na2O6(μ-O)2} core with two bridging carbonyl O atoms and two hydroxamate O atoms of two mono-deprotonated residues of N-hydroxypicolinamide, while two neutral N-hydroxypicolinamide molecules are coordinated in a monodentate manner to each sodium ion via the carbonyl O atoms [the Na—O distances range from 2.3044 (2) to 2.3716 (2) Å]. The pentacoordinated sodium ion exhibits a distorted trigonal–pyramidal coordination polyhedron. In the crystal, the coordination dimers are linked into chains along the c axis via N—H⋯O and N—H⋯N hydrogen bonds; the chains are linked into a two-dimensional framework parallel to (100) via weak C—H⋯O and π–π stacking interactions.The title compound, [Na Coordination of the μ-O carbonyl and hydroxamate O atoms of the same anion lead to the formation of five-membered chelate rings [Na1—O6i = 2.3716 (14) Å and O5i—Na—O6i = 70.26 (5)°]. Two neutral N-hydroxypicolinamide molecules coordinate in a monodentate manner to each sodium ion via the carbonyl O atoms [Na1—O1 = 2.3300 (16) Å and Na1—O3 = 2.3225 (15) Å]. As a result, each pentacoordinated sodium ion reveals a distorted trigonal–pyramidal coordination polyhedron  Å and the deviation of the O—Na—O angles from ideal values are up to 23.47 (5)°. The Na—O bond lengths are in the range 2.3044 (14)—2.3716 (14) Å, which is common for pentacoordinated sodium cations 2 core is virtually planar and approaches a square [the O—Na—O angles are 86.43 (5) and 93.57 (5)°].The molecular structure of title compound is shown in Fig. 1N-hydroxypicolinamide act as donors . The nearly coplanar pyridine rings of two neutral molecules of N-hydroxypicolinamide coordinating to the same sodium ion reveal intramolecular stacking interactions in unusual ‘head-to-head’ manner .The deprotonated hydroxamate atom O6 acts as an acceptor of two hydrogen bonds Table 1 in whichN-hydroxypicolinamide residue adopts a strongly flattened conformation with a dihedral angle of only 0.6 (2)° between the hydroxamic group and the pyridine ring. At the same time, the corresponding dihedral angles in both neutral N-hydroxypicolinamide molecules are noticeably greater [17.5 (2) and 8.9 (2)°], indicating a deviation of the hydroxamic group from the plane of pyridine rings. The configuration about the hydroxamic C—N bond is Z and that about the C—C bond between the pyridine and hydroxamic groups is E for both the neutral and deprotonated hydroxamates. Intramolecular N—H⋯N attractive contacts between the hydroxamate group and the nitrogen atom of pyridine ring [2.25 (2)–2.35 (3) Å] are present in both the neutral and deprotonated N-hydroxypicolinamide molecules  and N1—H1⋯N6 hydrogen bonds supported by a pair of weak non-classical C17—H17⋯N2 hydrogen bonds  hydrogen bond and π–π stacking between the N4/C7–C11 pyridine ring and the deprotonated O5/C18/N5/O6 hydroxamic group . Intermolecular π–π stacking between the same deprotonated hydroxamic group and the N2/C1–C5 pyridine ring  links the frameworks into a three-dimensional structure.In the crystal Fig. 2, the dims Table 1. The chaet al., 2016N-hydroxypicolinamide revealed the crystal structures of over 20 compounds, mostly belonging to the metallacrown (MC) family. In particular, heterometallic copper(II) 15-metallacrown-5 complexes with encapsulated GdIII and EuIII ions ,picHA-4](OTf)1.25(OH)0.75 ,picHA-4]2(OH)3(py)2 ,picHA-4]2··(pyridine)8·(triflate)3 2(OAc)4(DMF)2 collapsed metallacrown complex has been structurally characterized  with sodium hydrogen carbonate . Colorless crystals suitable for X-ray diffraction were obtained from the resulting aqueous solution by slow evaporation at ambient temperature within 48 h (yield 78%).The title compound was obtained by the reaction of Uiso = 1.2Ueq(C), and H atoms of the N—H and O—H groups were refined isotropically.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989016019095/xu5895sup1.cifCrystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989016019095/xu5895Isup2.hklStructure factors: contains datablock(s) I. DOI: 1520114CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The HCO3− transport across the luminal membrane has been proposed to be mediated by SLC26A Cl−–HCO3− exchangers. To examine the electrophysiological properties of Cl−–HCO3− exchangers, we directly measured HCO3− conductance in the luminal membrane of the interlobular pancreatic duct cells from guinea pigs using an inside-out patch-clamp technique. Intracellular HCO3− increased the HCO3− conductance with a half-maximal effective concentration value of approximately 30 mM. The selectivity sequence based on permeability ratios was SCN− (1.4) > Cl− (1.2) = gluconate (1.1) = I− (1.1) = HCO3− (1.0) > methanesulfonate (0.6). The sequence of the relative conductance was HCO3− (1.0) > SCN− (0.7) = I− (0.7) > Cl− (0.5) = gluconate (0.4) > methanesulfonate (0.2). The current dependent on intracellular HCO3− was reduced by replacement of extracellular Cl− with gluconate or by H2DIDS, an inhibitor of Cl−–HCO3− exchangers. RT-PCR analysis revealed that the interlobular and main ducts expressed all SLC26A family members except Slc26a5 and Slc26a8. SLC26A1, SLC26A4, SLC26A6, and SLC26A10 were found to be localized to the luminal membrane of the guinea pig pancreatic duct by immunohistochemistry. These results demonstrate that these SLC26A Cl−–HCO3− exchangers may mediate the electrogenic HCO3− transport through the luminal membrane and may be involved in pancreatic secretion in guinea pig ducts.The pancreatic duct epithelium secretes the HCO However, ducts secrete a HCO3−-rich fluid, which is dependent on the presence of CO2/HCO3−-buffer, and that neutralizes acid chyme in the duodenum [3− transport involves Cl−–HCO3− exchangers that operate in parallel with cAMP-activated Cl− channels [cystic fibrosis transmembrane conductance regulator (CFTR)] and Ca2+-activated Cl− channels, such as TMEM16A/ANO1, on the luminal membranes of duct cells -5-thiazolidinylidene]methyl]benzoic acid  and 2-methyl-8-(phenylmethoxy)imidazopyridine-3-acetonitrile  were dissolved in DMSO at a 1000-fold concentration for application. The current was recorded in the inside-out configuration using the EPC 800 patch-clamp amplifier (HEKA). The amplifier was driven by Clampex 9 (Axon) in order to allow the delivery of a voltage-ramp protocol with concomitant digitization of the current. The membrane potential was generally held at 0 mV, and the command voltage was varied from − 80 to + 80 mV over a duration of 800 ms every 10 s.Standard patch-clamp techniques were used. Patch pipettes, pulled from capillaries of hard borosilicate glass , had a resistance of 5–7 MΩ when filled with a standard Taq DNA Polymerase (Promega). The amplification parameters used were as follows: 1 cycle at 50 °C for 30 min and 1 cycle at 95 °C for 15 min, followed by 40 cycles at 94 °C for 30 s, 57 °C for 30 s, 72 °C for 30 s, and 1 cycle at 72 °C for 10 min. The transcripts were subsequently verified by agarose gel electrophoresis.RNA was extracted from the interlobular (outside diameter of 50–150 μm) and main ducts (outside diameter of around 500 μm) from three independent guinea pigs using the RNeasy Plus Micro kit with DNase I (Qiagen). RT-PCR analysis was performed using the OneStep RT-PCR kit (Qiagen) with primers designed to recognize different types of transporters (Table n = 3) in accordance with protocols approved by the Animal Experimentation Committee, Kansai Medical University. The guinea pigs were anesthetized with isoflurane and a mixture of medetomidine (0.5 mg/kg body weight), midazolam (5.0 mg/kg b.w.), and butorphanol (2.5 mg/kg b.w.), and perfused transcardially with 4% paraformaldehyde. The pancreas was fixed with 4% paraformaldehyde in PBS for 24 h, embedded in paraffin, and sectioned. Detailed methods for immunohistochemistry were described previously [Immunolocalization was performed on the guinea pig pancreas. The pancreas was obtained from female Hartley guinea pigs  on ice for 30 min, and then centrifuged. The pellet was solubilized in lysis buffer containing urea (9 M), Triton X-100 2%), dithiothreitol (1%), and lithium dodecyl sulfate (2%). The samples (30 μg/lane protein) were fractionated on SDS polyacrylamide gel (7.5%), electroblotted to PVDF membranes (Merck Millipore), blocked with skim milk (1%), and reacted with anti-SLC26A4, anti-SLC26A6, or anti-SLC26A10 antibodies  or Student’s paired I–V) relationships in the presence of intracellular HCO3− at different concentrations . As we used the standard NMDG-Cl pipette solution and the bathing solution containing KHCO3, the inward current was due to HCO3− efflux through the luminal membrane. The inward conductance determined from the linear section of the I–V relationships (from − 80 to − 60 mV) increased with intracellular HCO3− concentration  value for the effects of HCO3− and Hill coefficient were 31.5 ± 5.1 mM and 3.5 ± 0.4 (n = 5), respectively. We also measured inward HCO3− currents in the bathing solution containing 130 mM NaHCO3. The inward conductance increased to 2.04 ± 0.95 nS in NaHCO3 from 0.34 ± 0.08 nS in NaCl . Thus, there was a minor contribution of K+ conductance under unstimulated conditions.We recorded macroscopic currents from excised inside-out patches from the luminal membrane of the interlobular pancreatic duct cells of guinea pigs under unstimulated conditions. Figure 3− in the intracellular bathing solution with other monovalent anions. Figure I–V relations recorded in the inside-out configuration with the standard NMDG-Cl pipette solution. In experiments where HCO3− in the bath was replaced with Cl− or gluconate (glc−), the reversal potential did not change, but inward conductance significantly decreased from 1.30 ± 0.09 nS in HCO3− to 0.64 ± 0.13 nS in Cl−  and from 1.69 ± 0.08 nS in HCO3− to 0.72 ± 0.14 nS in glc− . Replacement of HCO3− with methanesulfonate (MES−) shifted the reversal potential in a negative direction, indicating it was less permeable than HCO3−, and the inward conductance significantly decreased from 2.56 ± 0.73 nS in HCO3− to 0.73 ± 0.36 nS in MES− . Replacement of HCO3− with thiocyanate (SCN−) slightly shifted the reversal potential in a positive direction, but the inward conductance had little change . Finally, replacement of HCO3− with iodide (I−) did not cause a marked difference in the reversal potential or the inward conductance . We calculated the permeability ratio (PX/PHCO3) from the shift in the reversal potential (ΔVrev) when anion X is substituted for internal HCO3− [− (1.41 ± 0.15) > Cl− (1.18 ± 0.14) = glc− (1.07 ± 0.03) = I− (1.06 ± 0.06) = HCO3− (1.00) > MES− (0.65 ± 0.11) (n = 5–6). The sequence of the relative inward conductance determined from − 80 to − 60 mV was HCO3− (1.00) > SCN− (0.69 ± 0.10) = I− (0.66 ± 0.09) > Cl− (0.48 ± 0.08) = glc− (0.43 ± 0.09) > MES− (0.26 ± 0.06) (n = 5–6).Ion selectivity of the bicarbonate conductance was examined by replacing 130 mM HCO−–HCO3− exchangers on the apical membrane of interlobular pancreatic ducts of the guinea pig, Ishiguro and colleagues replaced Cl− with gluconate in the lumen [−. With the control intracellular solution,Erev was − 46.6 ± 4.5 mV with a standard NMDG-Cl pipette solution  and − 63.6 ± 3.9 mV with gluconate-rich pipette solution , demonstrating a significant difference (ANOVA). We also compared the inward HCO3− conductance with gluconate-rich and standard NMDG-Cl pipette solutions  than with standard NMDG-Cl pipette solutions (1.30 ± 0.09 nS) . Additionally, as described in the previous section, the inward conductance significantly decreased when HCO3− in the bath was replaced with Cl−, indicating that there was a minor contribution from Cl−-dependent current  intracellularly while recording macroscopic currents from excised inside-out patches with the control bicarbonate internal and the standard NMDG-Cl pipette solutions. To exclude the possibility of the contamination of CFTR Cl− conductance, we included 20 μM CFTRinh-172, an inhibitor of CFTR Cl− channels, in the pipette solution. H2DIDS applied intracellularly significantly decreased inward HCO3− conductance from 1.57 ± 0.55 to 0.86 ± 0.37 nS . We also tested 30 μM Sch28080, a H+–K+-pump inhibitor, but did not observe any inhibitory effects on the inward HCO3− conductance . These results further support that the HCO3− conductance occurs through Cl−–HCO3− exchangers.Previous studies reported that Clstilbene , 43. For2+ signaling pathways play a role in fluid secretion. As CFTR Cl− channels were regulated by intracellular cAMP [n = 13). The addition of 1 mM cAMP further increased the inward conductance to 14.8 ± 5.57 nS (n = 4). cAMP also activated the marked outward conductance, which was attributed to Cl− influx, most likely through CFTR Cl− channels. Therefore, we tested the effects of intracellular ATP-Mg and cAMP with the pipette solution including CFTRinh-172 at 20 μM. In the presence of CFTRinh-172, application of intracellular 2 mM ATP-Mg and 1 mM cAMP had little effect on the conductance in either direction . These results indicate that intracellular ATP and cAMP may not directly regulate Cl−–HCO3− exchangers, but instead regulate CFTR Cl− channels on the luminal membrane of duct cells. Additionally, 1 μM free Ca2+ added to the intracellular solution did not affect the inward HCO3− conductance , suggesting that intracellular Ca2+ does not regulate Cl−–HCO3− exchangers directly.In pancreatic duct cells, cAMP and Calar cAMP , 8, 29 alar cAMP , we test−–HCO3− exchangers [Slc26a3 and Slc26a6 [n = 3 animals) and main ducts , along with GAPDH and a duct marker of carbonic anhydrase II (CA2). We also screened all primer sets from the total RNA of the kidney as a positive control . The molecular mass values corresponded to those of human SLC26A proteins (~ 100 kDa), which were N-glycosylated, expressed in HEK-293 cells [We next performed western blot analysis to examine the expression of SLC26A protein in the guinea pig pancreatic ducts. We detected SLC26A6 (~ 107 kDa), SLC26A1 ~ 78 kDa), SLC26A4 (~ 136 kDa), and SLC26A10 (~ 108 kDa) in the lysates of the isolated ducts  of 160 and 80 μM, respectively [−–HCO3− exchangers from not only the outside but also from the inside of the cell membrane.We found that Hane Fig. . A previectively . It is l3− conductance through the luminal membrane is mediated by Cl−–HCO3− exchangers under physiological HCO3− concentrations in pancreatic duct cells. Our findings suggest that SLC26A1, SLC26A4, SLC26A6, and SLC26A10 may be involved in the HCO3− transport through the luminal membrane. The SLC26A family may also play a role in pH homeostasis in the pancreatic lumen and duct cells. The direct measurement of the HCO3− current from the interlobular duct and its functional characterization helps to propose a useful model for HCO3− secretion from the pancreatic duct epithelia (Fig. In conclusion, we used the patch-clamp technique in the inside-out configuration and demonstrated that the HCOlia Fig. .Fig. 9Mo


II cations are bridged by S atoms from the N,N-diallylldithiocarbamate ligands.The characteristic feature of this cadmium(II) complex is the formation of a dimeric bridged structure where the two Cd 2(C7H10NS2)4], is a neutral dinuclear cadmium(II) complex bearing four bis N,N-diallyldithiocarbamate ligands coordinating to two CdII cations. In each of the monomeric subunits, there are four S atoms of two dithiocarbamate ligands  that coordinate to one CdII atom in a bidentate mode. The dimers are located over an inversion centre bridged by two additional bridging Cd—S bonds [2.6021 (3) Å], leading to a substantial distortion of the geometry of the monomeric subunit from the expected square-planar geometry. The five-coordinate environment around each of the CdII ions in the dimer is best described as substantially tetragonally distorted square pyramidal. The dithiocarbamate groups are themselves planar and are also coplanar with the CdII ions. The negative charge on these groups is delocalized by resonance across the S atoms bound to the CdII cation. This delocalization of the π electrons in the dithiocarbamate groups also extends to the C—N bonds as they reveal significant double bond character [C—N = 1.3213 (16) and 1.3333 (15) Å].The title compound, [Cd This common feature has been ascribed to the effect of aggregated species, which they adopt in the solid state, resulting from equal numbers of μ2-tridentate and bidentate (chelating) ligands cadmium compounds have the advantage of having stability similar to that of the zinc complexes, but more favourable stability when compared to the mercury complexes. Cadmium dithiocarbamate complexes have been widely used as single-source precursors for CdS nanoparticles and thin films, which have application as non-linear optical materials  to 2.8016 (3) Å and to a fifth S atom at a distance of 2.6021 (3) Å; these distances are similar to other complexes found to have been published previously (see Section 4: Database survey). A full geometry check carried out with the Mogul Geometry Check tool  –x + 2, –y, –z + 1]. This means that each bridging S atom simultaneously occupies an equatorial coordination site on one CdII ion and an apical site on the other CdII ion to form an edge-shared tetragonal–pyramidal geometry. The CdII ion deviates from the S11—S12—S22—S21 mean plane by 0.704016 (17) Å towards S12i. The bridging network Cd1—S12—Cd1i—S12i is completely planar since it lies over the inversion centre with a Cd1⋯Cd1i separation distance of 3.60987 (8) Å and S12—Cd1—S12i and Cd1—S12—Cd1i angles of 96.257 (9) and 83.743 (9)°, respectively. There is substantial distortion of the geometry of the monomeric subunit from the expected square-planar geometry. Deviations from the standard 90° angles are evident in the angles of S11—Cd1—S21 [108.203 (11)°]; S22—Cd1—S21 [70.264 (10)°]; S22—Cd1—S12 [96.950 (10)°] and S11—Cd1—S12 [67.486 (10)°]. Deviations in the standard 180° angles are evident in the angles of S11—Cd1—S22 [143.705 (13)°] and S21—Cd1—S12 [152.651 (11)°]. The Cd1—S12—Cd1i—S12i and S11—S12—S22—S21 mean planes form a dihedral (twist) angle of 84.6228 (18)°. The dithiocarbamate groups are planar and each group of the monomeric subunit is coplanar with the CdII ion (r.m.s. deviation is 0.010 Å). The mean plane consisting of atoms Cd1, S11, N1, C11, S12 and the mean plane consisting of atoms Cd1, S22, N2, C21, S21 have a plane-normal-to-plane-normal angle of 37.0291 (10)°; a centroid-to-centroid distance of 4.45354 (8) Å; a plane-to-plane shift of 4.22298 (8) Å and a plane-to-plane torsion (twist) angle of 8.0304 (12)°.The coordination environment of the Cdry Fig. 1. The CdIII cation. On the opposite side of the CdII ion, both S—C bonds have approximately the same length, where S21—C21 and S22—C21 bond lengths are 1.7224 (12) and 1.7263 (12) Å, respectively, suggesting that the double bond of the dithiocarbamate is spread over the S—C—S bond via resonance. A possible explanation for this may be because of the fact that atom S12 serves as the bridging S atom in the complex. Also, the N1—C11 and N2—C21 distances  are shorter compared to the other N—C distances indicating considerable double-bond character. The vinyl substituents are also planar and are at an angle of 91.6049 (14)° from the dithiocarbamate plane and at an angle of 150.9196 (6)° from the vinyl group directly opposite from it. This scenario is comparable with the other structures surveyed in the literature (see Section 4: Database survey). All highlighted and discussed geometrical parameters describing the coordination environment are given in Table 1The S12—C11 bond length [1.7532 (13) Å] is longer than the adjacent S11—C11 bond length [1.7162 (13) Å] suggesting that this bond has more double bond character in the dithiocarbamate portion that coordinates to the CdPThe space group of the crystal is et al., 2016N,N-diallyl side chain, the side-chains substituents are di-n-propyl [CSD refodes BEHNOR   in ethanol (10 ml) was added to a solution of sodium N,N-diallyl dithiocarbamate  in ethanol (10 ml), and the resulting suspension was stirred for 45 min at room temperature. This solution was then filtered, and rinsed several times with distilled water  has been published previously  = 1.2 Ueq(C) for methylene groups and C—H = 0.95 Å and Uiso(H) = 1.2 Ueq(C) for all vinyl groups.Crystal data, data collection and structure refinement details are summarized in Table 410.1107/S2056989017011616/zl2710sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989017011616/zl2710Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017011616/zl2710Isup3.molSupporting information file. DOI: 899314CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


N′-aminopyridine-2-carboximidamide (C6H8N4), 1, and N′-{[1-(pyridin-2-yl)ethylidene]amino}pyridine-2-carboximidamide (C13H13N5), 2, molecules are linked by intermolecular N—H⋯N hydrogen-bonding interactions, forming a two-dimensional network in 1 and a chain in 2.In the crystal structures of  N′-aminopyridine-2-carboximidamide (C6H8N4), 1, and N′-{[1-(pyridin-2-yl)ethylidene]amino}pyridine-2-carboximidamide (C13H13N5), 2, are described. The non-H atoms in compound 1 are nearly planar (r.m.s. deviation from planarity = 0.0108 Å), while 2 is twisted about the central N—N bond by 17.8 (2)°. Both molecules are linked by intermolecular N—H⋯N hydrogen-bonding interactions; 1 forms a two-dimensional hydrogen-bonding network and for 2 the network is a one-dimensional chain. The bond lengths of these molecules are similar to those in other literature reports of azine and diimine systems.The crystal structures of  RC(=NH)NHNH2 is accomplished by the action of hydrazine on the corresponding thioamide, imido ether or nitrile  of the heterocyclic ligand  and 0.24 (6) Å out of the mean plane of non-hydrogen atoms. For H4A and H4B, the deviation is even greater at 0.37 (5) and 0.54 (5) Å from the mean plane. Rotation of the non-planar NH2 group, particularly for N4, facilitates hydrogen bonding to other molecules. The N—N single bond length in 1 [1.424 (5) Å] is slightly shorter than that in the free hydrazine (1.449 Å).The molecular structure of 2 is shown in Fig. 2The molecular structure of E,E conformation, suggesting conjugation throughout the π systems. The C6—N2—N3 and C8—N3—N2 angles of 115.5 (2)° and 110.57 (19)°, respectively are significantly below the ideal sp2 value of 120°, a consequence of the repulsion between the nitrogen lone pair and the adjacent bonds. The C6—N2—N3—C8 torsion angle is −162.2 (2)°. This large deviation from planarity has two consequences. First, there is a loss of conjugation between the imine bonds across the azine bond, reflected in the shorter imine bond length. The torsion also leads to a shorter N2—N3 bond length [1.408 (3) Å] compared to that observed for 1 [1.424 (5) Å]. Finally, a short intramolecular contact between N3i and H4B, 2.42 (3) Å, may add a favorable electrostatic contribution to the stability of this conformation. Notably, there is minimal change in the bond lengths within the ligands when a first row transition metal ion is bound. When the ligand chelates to a metal ion through both N3 and N5, only the bond length C8—N4 changes significantly, becoming shorter on binding.The bond lengths indicate that within the central chain of the molecule, the C6—N2 and C8—N3 linkages have largely double-bond character. The azine linkages are in the 1 in each unit cell and these are related by the screw axis. Curiously, N1 does not act as a hydrogen-bond acceptor. H2A is also not involved with the formation of any (short) classical hydrogen bonds. H2B forms a hydrogen bond to N4i . This is augmented by the longer hydrogen bond N4—H4B⋯N4i. N4—H4A forms a hydrogen bond to N3ii . These three sets of hydrogen bonds  1/2 – x, 1 – y, z – 1/2] is present and this knits the molecules of 2 together to form hydrogen-bonded chains along the [001] direction, as shown in Fig. 4The classical hydrogen bonding Table 2 in 2 is N′-aminopyridine-2-carboximidamide and related molecules, see Case et al. (1965N′-{[1-(pyridin-2-yl)ethylidene]amino}pyridine-2-carboximidamide and analogues, see Gokhale et al. ethylidene]amino}pyridine-2-carboximidamide is depicted in Fig. 5The synthesis of N′-Aminopyridine-2-carboximidamide (1) was prepared by an analogy of the procedure published by Case (1965N′-{[1-(Pyridin-2-yl)ethylidene]amino}pyridine-2-carboximidamide (2) was synthesized by an analogy of the procedure published by Gokhale et al.  to 0.99 (3) Å. The other hydrogen atoms attached to formally single-bonded nitrogen atoms were freely refined subject to sensible distance and angle restraints. The N—H distances lie in the range 0.94 (3)-0.95 (3) Å.For compound 2, hydrogen atoms were placed using a riding model .For compound 10.1107/S2056989017008416/nk2236sup1.cifCrystal structure: contains datablock(s) 1, 2. DOI: 10.1107/S2056989017008416/nk22361sup2.hklStructure factors: contains datablock(s) 1. DOI: Click here for additional data file.10.1107/S2056989017008416/nk22361sup4.cdxSupporting information file. DOI: 10.1107/S2056989017008416/nk22362sup3.hklStructure factors: contains datablock(s) 2. DOI: Click here for additional data file.10.1107/S2056989017008416/nk22362sup5.cdxSupporting information file. DOI: Click here for additional data file.10.1107/S2056989017008416/nk22361sup6.cmlSupporting information file. DOI: Click here for additional data file.10.1107/S2056989017008416/nk22362sup7.cmlSupporting information file. DOI: 1554569, 1554568CCDC references:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


Molecules containing multiple bonds between atoms—most often in the form of olefins—are ubiquitous in nature, commerce, and science, and as such have a huge impact on everyday life. Given their prominence, over the last few decades, frequent attempts have been made to perturb the structure and reactivity of multiply-bound species through bending and twisting. However, only modest success has been achieved in the quest to completely twist double bonds in order to homolytically cleave the associated π bond. Here, we present the isolation of double-bond-containing species based on boron, as well as their fully twisted diradical congeners, by the incorporation of attached groups with different electronic properties. The compounds comprise a structurally authenticated set of diamagnetic multiply-bound and diradical singly-bound congeners of the same class of compound. Attempts to bend and twist multiple bonds in order to alter their reactivities have thus far been met with only modest success. Here, Braunschweig and colleagues isolate double-bond-containing boron-based species and their 90°-twisted diradical analogs, thanks to their stabilization with Lewis basic units. Having one degree of electronic unsaturation more than relatively inert alkanes, olefins are the simplest and most earth-abundant hydrocarbons that show reactivity under ambient conditions, leading to their widespread industrial use as well as their implication in questions related to the origins of life4. Olefins are molecules that contain a double bond between two carbon atoms consisting of one bond of σ symmetry and one of π symmetry  olefin by 90° would completely break its π bond, presumably leading to a triplet diradical  due to their necessarily twisted geometry.The π orbital of olefins requires the parallel alignment of two carbon cal Fig. , right a18. Beyond carbon–carbon double bonds, sterically hindered heavier olefin analogs such as disilenes (of the form R2Si = SiR2) also withstand significant twisting of the double bond (up to 55°)23. In a key 2015 study, Sekiguchi and coworkers reported that one of these disilenes (Si2(SiMetBu2)4) was able to thermally populate a triplet state by twisting of the  Si=Si bond above 77 °C. This diradical compound was characterized by electron paramagnetic resonance (EPR) spectroscopy and calculated to have an average SiSiSiSi dihedral angle of 75.2°; however, its structure could not be authenticated experimentally22. This work remains the forefront of chemists’ efforts to isolate the diradical products of twisting element–element double bonds.It is thus unsurprising that efforts to isolate “twisted olefin” compounds have resulted in only partial success: isolation of diamagnetic, incompletely twisted structures 27, as well as their 90°-twisted diradical congeners 2 imidazol-2-ylidene) led to new 11B NMR signals to higher field of that of the triply-bound precursor (δB 39)24, signifying the formation of three new products, 1a–c  or purple  solids with 11B NMR signals  in a similar range to those of known doubly NHC-stabilized diborenes (δB 18–28)27, but significantly more downfield than those of two previously observed diboratellurirenium cations (cyclo-[Te(R)B(NHC)B(NHC)]+) prepared by the analogous reactions of B2(IDip)2 with diphenylditelluride (δB 0)35. Single-crystal X-ray diffraction confirmed the trans-diborene nature of 1a–c, all three molecules displaying effectively planar LRB=BRL double bond units  Å; 1b: avg. 1.568(6) Å; 1c: avg. 1.565(5) Å).Simple room-temperature (RT) addition of either equal amounts or slight excesses of dibutyldisulfide, diphenyldisulfide, or diphenyldiselenide to solutions of the triple-bond-containing diboryne species Ba–c Fig. , top. Afits Fig. , top, an2(IDip)2 (B2(CAAC)2; CAAC = 1--3,3,5,5-tetramethylpyrrolidin-2-ylidene)36. However, to our surprise, all three reaction mixtures became very dark, and all attempts to obtain NMR spectra from the mixtures gave either silent spectra or exceptionally broad signals well outside the normal diamagnetic chemical shift ranges. Solvent extraction and recrystallization provided the black solids 2a–c °; 2b: 100.9(1)°; 2c: 99.7(2)°), and long, single B–B bonds (2a: 1.728(2) Å; 2b: 1.713(2) Å; 2c: 1.700(4) Å). On either side of the midpoint of the molecules, the N-C-B-S/Se units are near-planar, with relatively small N-C-B-S/Se torsion angles (2a: 1.7(2)°, 14.6(2)°; 2b: 17.4(2)°, 1.5(2)°; 2c: 18.7(3)°, 0.1(4)°) suggesting significant π-electron delocalization over this portion of the molecule. The B-S/Se distances of 2a–c (d(B–S): 1.84–1.86 Å; d(B–Se): 1.99–2.00 Å) were found to be slightly shorter than those of 1a–c (d(B–S): 1.88–1.92 Å; d(B–Se): 2.01–2.06 Å), and the B–C distances of 2a–c (1.53–1.55 Å) are likewise shorter than those of 1a–c (1.57–1.62 Å).We also attempted the analogous addition of dibutyldisulfide, diphenyldisulfide, or diphenyldiselenide to solutions of a more cumulenic CAAC analog of Ba–c Fig. , bottom.2a–c, the apparent absence of B–B multiple bonding, and the inability to procure NMR data of the compounds suggested that they may be captodatively stabilized30 triplet diradicals, each with two push–pull systems involving the π-donating S/Se atom and the π-accepting CAAC carbene carbon atom –B(•)RL; Fig. 2a–c are reminiscent of our related neutral monoradical species [DurB(Cl)(CAAC)]• reported in 201431. In order to confirm the diradical nature of 2a–c, we performed EPR spectroscopy on 2a–c in frozen 2-methyltetrahydrofuran glass. While we observed an intense half-field transition for 2a and 2b  due to dipole interaction, indicating that the spin system in question is a triplet state. Analysis of the spectra yields estimates of the ZFS parameters , the axial parts of which correspond to interspin distances of 4.5 and 4.4 Å (assuming point dipole approximation), respectively. These distances are significantly longer than the ca. 1.70–1.73 Å boron–boron distances found by X-ray crystallography, and match better the distance between the two CAAC carbene carbon atoms . Thus, the two unpaired electrons must be significantly delocalized into the substituents, most likely toward the carbene carbon atoms, which is in line with that expected by the captodative effect of the π-donor nitrogen and π-acceptor boron atoms.The significantly greater delocalization in the C-B-S/Se portion of  2b Fig. –16, only2a, temperature-dependent magnetic measurements were performed on a solid sample  lower than the singlet state. The exchange coupling determined from solid-state SQUID measurements is also reflected to some degree in the temperature-dependence of the signal intensities observed in the solution-state EPR spectra of 2a  and single B–B bond character in 2a–c . Figure 1a–c and diradicals 2a–c. The former, as exemplified by 1a, possess highest occupied molecular orbitals , with lower but roughly equivalent spin density on the B (0.18 and 0.23 e) and N (0.21 and 0.22 e) atoms.Density functional theory (DFT) calculations for diamagnetic diborenes  2a Fig.  show tha2a. The overestimation may result from the need for multi-reference approaches38 to describe the singlet and triplet states on equal footing. Because 2a is too large for such costly approaches, we investigated the error of the DFT approaches for a smaller model system , the values obtained with DFT range from –4 to –28 kcal mol–1. The MN12-L/6–311G approach used to estimate the S–T gap of the full system 2a overestimates the stability of the triplet state by about 6–7 kcal mol–1. Transferring this error to the predictions of the MN12L41/6–311G43 approach for the full system 2a , a near-zero S–T gap results, which is in line with the measured value.While DFT computations and experiment agree in terms of geometry and the energetic order of the singlet and triplet states, the DFT computations considerably overestimate the size of the singlet–triplet gap (S–T gap) of compound 2a–c also distinguishes these diradicals from diborenes 1a–c , as previously observed for related diborenes44. In contrast, diradicals 2a–c show less-facile oxidation events, with additional reduction waves, in line with the presence of the more π-accepting CAAC ligands. It should also be noted that variable-temperature NMR experiments suggest that the diamagnetic diborenes 1 and the diradical species 2 do not convert to their alternative conformations upon heating to 80 °C.The electrochemical behavior of 1a–c and their twisted congeners 2a–c marks the first isolation and structural authentication of diamagnetic, multiply-bound molecules and their diradical, single-bond congeners, products of formal homolysis of the central multiple bond. Crystallographic, EPR spectroscopic, magnetic and theoretical studies confirm that 2a–c are diradical species. Spectroscopic and computational studies also confirm the substantial energy differences between the singlet and triplet states of the molecules, with the singlet states being favored in 1a–c and the triplet states in 2a–c.The synthesis of diborenes 1H: 500.13 MHz, 11B: 160.46 MHz, 13C{1H}: 125.76 MHz) at RT. Chemical shifts (δ) are given in ppm and internally referenced to the carbon nuclei (13C{1H}) or residual protons (1H) of the solvent. 11B NMR spectra were referenced to the external standard [BF3·OEt2]. Microanalyses  were performed on an Elementar vario MICRO cube elemental analyzer. Melting points were determined with a Mettler Toledo 823e DSC in sealed ampules with a ramp rate of 10 °C min−1. UV/vis absorption spectra 2(SBu)2, (1a): Dibutyldisulfide  was added dropwise to a stirred solution of B2(IDip)2  in pentane (10 mL). The mixture was stirred for 18 h at RT and all volatiles were removed in vacuo. The dark green residue was dried in vacuo at 80 °C for 2 h to remove the excess dibutyldisulfide, extracted with 5 mL pentane, and crystallized from a slowly evaporating hexane/ether solution. The crystalline material was washed with pentane (2 × 1 mL) yielding 73.4 mg  of pure 1a as a green solid. 1H NMR : δ = 7.19–7.14 , 7.04 , 7.02 , 6.36 , 3.02 , 1.74 , 1.23 , 1.17–1.05 , 0.98 , 0.88 . 13C NMR  δ = 176.8 (CNHC), 147.0 (Cq), 139.2 (Cq), 129.1 (CHAryl), 124.4 (CHAryl), 123.8 (CHNHC), 43.1 (SBu-CH2), 34.9 (SBu-CH2), 29.1 (CHiPr), 26.2 (iPr-CH3), 24.3 (iPr-CH3) 24.0 (SBu-CH2), 14.7 (SBu-CH3). 11B NMR : δ = 30 (s) ppm. Elemental analysis calculated for C62H90B2N4S2[+hexane]: C 76.81%, H 9.86%, N 5.27%, S 6.03%; found: C 76.86%, H 9.63%, N 5.62%, S 5.82%.Synthesis of B2(IDip)2(SPh)2, (1b): B2IDip2  and diphenyldisulfide  were dissolved in benzene (10 mL) and stirred for 14 h. The solvent was evaporated and the residue was extracted with pentane (2 × 5 mL). The pentane phase was removed under vacuum giving pure 1b  as a purple solid. Suitable crystals for X-ray diffraction were obtained by slow evaporation of a pentane solution. Decomp.: 221 °C. 1H NMR : δ = 7.04 , 6.91 , 6.85 , 6.79 , 6.29 , 3.20 , 1.05 , 0.97  ppm. 13C NMR  δ = 174.7 (Cq), 148.8 (Cq), 146.3 (Cq), 137.6 (Cq), 129.3 (CHAryl), 128.9 (CHAryl), 127.7 (CHAryl), 124.2 (CHAryl), 124.0 (CHNHC), 120.1 (CHAryl), 28.9 (CHiPr), 26.6 (iPr-CH3), 22.7 (iPr-CH3) ppm. 11B NMR : δ = 25 (s) ppm. Elemental analysis calculated for C66H82B2N4S2: C 77.94%, H 8.13%, N 5.51%, S 6.30%; found: C 78.12%, H 8.26%, N 5.58%, S 6.25%.Synthesis of B2(IDip)2(SePh)2, (1c): A solution of B2IDip2  and 1,2-diphenyldiselenide  in benzene (10 mL) was stirred for 14 h. After the solvent was removed, the residue was extracted with pentane (2 × 5 mL). The solvent was evaporated under vacuum giving pure 1c  as a purple solid. Suitable crystals for X-ray diffraction were obtained by slow evaporation of a pentane solution. Decomp.: 128 °C. 1H NMR : δ = 7.05 , 6.96 , 6.93 , 6.88 , 6.76 , 6.33 , 3.29 , 1.02 , 0.98  ppm. 13C NMR  δ = 174.7 (Cq) 146.5 (Cq), 143.2 (Cq), 137.53 (Cq), 137.52 (Cq), 131.3 (CHAryl), 129.5 (CHAryl), 127.7 (CHAryl), 124.3 (CHAryl), 124.1 (CHNHC), 121.3 (CHAryl), 29.0 (CHiPr), 26.7 (iPr-CH3), 22.8 (iPr-CH3) ppm. 11B NMR : δ = 22 (s) ppm. 77Se NMR : δ = 175.6 ppm. Elemental analysis calculated for C66H82B2N4Se2: C 71.36%, H 7.44%, N 5.04%; found: C 70.68%, H 7.66%, N 4.66%.Synthesis of B2(CAAC)2(SBu)2, (2a): Dibutyl disulfide  was added dropwise to a stirred solution of B2(CAAC)2  in pentane (20 mL) at –40 °C. The mixture was stirred for 24 h at RT and all volatiles were removed in vacuo. The dark yellow solid was dried in vacuo, dissolved in hexane (10 mL), and black crystals were obtained by slow evaporation of the solvent. The crystalline material was washed with pentane (2 × 1 mL) yielding 291 mg  of pure 2a as a black solid. Elemental analysis calculated for C48H80B2N2S2: C 74.78%, H 10.46%, N 3.63%, S 8.32%; found: C 75.15%, H 10.37%, N 3.70%, S 8.01%.Synthesis of B2(CAAC)2(SPh)2, (2b): Pentane (20 mL at –40 °C) was added to a mixture of B2(CAAC)2  and diphenyl disulfide . The mixture was stirred for 3 h at RT, filtered and the residual solid was washed with pentane (3 × 5 mL). The brown solid was dried in vacuo, dissolved in benzene (10 mL), and black crystals were obtained by slow evaporation of the solvent. The crystalline material was washed with pentane (2 × 1 mL) yielding 53.4 mg  of pure 2b as a black solid. Decomp.: 138 °C. Elemental analysis calculated for C52H72B2N2S2: C 77.02%, H 8.95%, N 3.45%, S 7.91%; found: C 77.57%, H 8.97%, N 3.36%, S 7.58%.Synthesis of B2(CAAC)2(SePh)2, (2c): Pentane (20 mL at –40 °C) was added to a mixture of B2(CAAC)2  and diphenyl diselenide . The mixture was stirred for 3 h at RT, filtered and the residual solid was washed with pentane (2 × 5 mL). The brown solid was dried in vacuo, dissolved in benzene (10 mL), and black crystals were obtained by slow evaporation of the solvent. The crystalline material was washed with pentane (2 × 1 mL) yielding 36.2 mg  of pure 2c as a black solid. Decomp.: 191 °C. Elemental analysis calculated for C52H72B2N2Se2: C 69.04%, H 8.02%, N 3.10%; found: C 69.24%, H 7.95%, N 2.74%.45. The EPR spectra of 2a and 2b show an intense half-field signal but only partially resolved zero-field splittings with no visible hyperfine structure. Attempts to improve the resolution by lowering the concentration or changing the solvent were not successful. For 2c, no clear sign of a triplet ground state could be obtained.EPR measurements at the X-band (9.4 GHz) were carried out using a Bruker ELEXSYS E580 CW EPR spectrometer equipped with an Oxford Instruments helium cryostat (ESR900) and a MercuryiTC temperature controller. The spectral simulations were performed using MATLAB 8.6.0.267246 (R2015b) and the EasySpin 5.1.9 toolboxVycor tip, serving as the reference electrode. Formal redox potentials are referenced to the ferrocene/ferrocenium ([Cp2Fe]+/0) redox couple by using ferrocene as an internal standard. Tetrabutylammonium hexafluorophosphate ([Bu4N][PF6]) was employed as the supporting electrolyte. Compensation for resistive losses (iR drop) was employed for all measurements.Cyclic voltammetry experiments were performed using a Gamry Instruments Reference 600 potentiostat. A standard three-electrode cell configuration was employed using a platinum disk working electrode, a platinum wire counter electrode, and a silver wire, separated by a 2IDip2(SBu)2 (1a), B2IDip2(SPh)2 (1b), B2IDip2(SePh)2 (1c), and B2CAAC2(SBu)2 (2a) were collected on a Bruker X8-APEX II diffractometer with a CCD area detector and multi-layer mirror-monochromated MoKα radiation. The structure was solved using the intrinsic phasing method (ShelXT)46, refined with the ShelXL program47, and expanded using Fourier techniques. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included in structure factor calculations. All hydrogen atoms were assigned to idealized geometric positions.The crystal data of BCrystal data for B2IDip2(SBu)2(1a): The displacement parameters of atoms C63–C74 were restrained to the same value with similarity restraint SIMU. C68H104B2N4S2, Mr = 1063.29, green block, 0.294 × 0.257 × 0.125 mm3, monoclinic space group P21/c, a = 14.423(5) Å, b = 12.522(5) Å, c = 36.640(17) Å, β = 96.25(3)°, V = 6578(5) Å3, Z = 4, ρcalcd = 1.074 g cm–3, μ = 0.122 mm–1, F(000) = 2328, T = 103(2) K, R1 = 0.0980, wR2 = 0.1550, 13420 independent reflections [2θ ≤ 52.744°], and 768 parameters. CCDC-1567701.Crystal data for B2IDip2(SPh)2(1b): C66H82B2N4S2, Mr = 1017.09, red block, 0.25 × 0.14 × 0.05 mm3, monoclinic space group P21/c, a = 22.2980(16) Å, b = 24.4556(17) Å, c = 42.972(3) Å, β = 91.133(2)°, V = 23428(3) Å3, Z = 16, ρcalcd = 1.153 g cm−3, μ = 0.134 mm–1, F(000) = 8768, T = 100(2) K, R1 = 0.1465, wR2 = 0.1925, 48137 independent reflections [2θ ≤ 52.746°], and 2730 parameters. CCDC-1567705.Crystal data for B2IDip2(SePh)2(1c): C66H82B2N4Se2, Mr = 1110.89, red block, 0.35 × 0.15 × 0.08 mm3, monoclinic space group P21/c, a = 22.4904(11) Å, b = 24.4964(13) Å, c = 43.042(2) Å, β = 91.335(2)°, V = 23707(2) Å3, Z = 16, ρcalcd = 1.245 g cm–3, μ = 1.291 mm–1, F(000) = 9344, T = 100(2) K, R1 = 0.0804, wR2 = 0.0917, 48482 independent reflections [2θ ≤ 52.744°], and 2729 parameters. CCDC-1567706.Crystal data for B2CAAC2(SBu)2(2a): C51H87B2N2S2, Mr = 813.96, orange block, 0.335 × 0.257 × 0.112 mm3, triclinic space group Pa = 10.383(5) Å, b = 14.048(9) Å, c = 17.857(8) Å, α = 75.299(15)°, β = 84.42(3)°, γ = 77.545(19)°, V = 2458(2) Å3, Z = 2, ρcalcd = 1.100 g cm–3, μ = 0.143 mm–1, F(000) = 898, T = 100(2) K, R1 = 0.0532, wR2 = 0.1087, 10053 independent reflections [2θ ≤ 52.744°], and 533 parameters. CCDC-1567703.2CAAC2(SPh)2 (2b) and B2CAAC2(SePh)2 (2c) were collected on a Bruker D8 Quest diffractometer with a CMOS area detector and multi-layer mirror-monochromated MoKα radiation. The structure was solved using the intrinsic phasing method (ShelXT)46, refined with the ShelXLprogram47, and expanded using Fourier techniques. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included in structure factor calculations. All hydrogen atoms were assigned to idealized geometric positions.The crystal data of BCrystal data for B2CAAC2(SPh)2(2b): C52H72B2N2S2, Mr = 810.85, orange block, 0.173 × 0.161 × 0.122 mm3, monoclinic space group P21/n, a = 9.9798(15) Å, b = 18.647(4) Å, c = 24.919(5) Å, β = 97.909(15)°, V = 4593.2(15) Å3, Z = 4, ρcalcd = 1.173 g cm–3, μ = 0.153 mm–1, F(000) = 1760, T = 100(2) K, R1 = 0.0422, wR2 = 0.0961, 9368 independent reflections [2θ ≤ 52.746°], and 539 parameters. CCDC-1567702.Crystal data for B2CAAC2(SePh)2(2c): C52H72B2N2Se2, Mr = 904.65, orange block, 0.061 × 0.055 × 0.025 mm3, monoclinic space group P21/n, a = 10.060(7) Å, b = 18.707(7) Å, c = 24.857(14) Å, β = 98.86(3)°, V = 4622(5) Å3, Z = 4, ρcalcd = 1.300 g cm–3, μ = 1.637 mm–1, F(000) = 1904, T = 100(2) K, R1 = 0.0628, wR2 = 0.0784, 9321 independent reflections [2θ ≤ 52.746°], and 539 parameters. CCDC-1567704.48, B3LYP51, and BP8652 levels in conjunction with the def2-SVP53 basis set. The structures were characterized as minima by frequency calculation. The NBO54 analyses were carried out at the M05-2X/def2-SVP level  calculations were carried out on diamagnetic diborenes 1a–c and the diradicals 2a–c in their singlet and triplet states  whereas the triplet states of 2a-c are always more stable than the singlet states  43 approach to optimize the geometry of the lowest-lying singlet and triplet states of 2a. Both optimizations were started from the X-ray structure of the triplet ground state. The computed singlet geometry does not represent the global minimum of the singlet potential energy surface, which possesses a nearly planar CCAAC-B-B-CCAAC orientation. However, only the local minimum lying near the triplet equilibrium structure will not be populated in the measurements because the global minimum of the singlet state is separated from the triplet equilibrium geometry by high-energy barriers. For the computed geometries , the MN12L/6–311G approach predicts an S–T gap of about –6.4 kcal mol–1 (triplet below singlet state).To obtain an estimate of the inaccuracies of DFT approaches, we first used the MN12L2aʹ in which we replaced the bulky substituents as indicated in Supplementary Figure 2a systems to include the influence of steric effects on the geometry. The model system 2aʹ contains all essential binding ingredients of 2a but is sufficiently small to perform high-level NEVPT240/def2-TZVP benchmark calculations for the S–T gap. To compare the predicted S–T gaps, we performed single-point calculations employing the geometries described above.To enable high-level multi-reference approaches, we then created a closely related model system −1 to nearly –29 kcal mol−1, showing that such DFT calculations have to be handled with care.The results are summarized in Supplementary Table Cartesian coordinates for all of the calculated compounds are given in Supplementary Table 2a were carried out with a Quantum-Design MPMS-XL-5 SQUID magnetometer equipped with a 5-Tesla magnet in the range from 295 to 2.0 K at a magnetic field of 0.5 T. The powdered sample was contained in a Teflon bucket and fixed in a non-magnetic sample holder. Each raw data file for the measured magnetic moment was corrected for the diamagnetic contribution of the Teflon bucket according to Mdia(bucket) = χg × m × H, with an experimentally obtained gram susceptibility of the Teflon bucket. The molar susceptibility data were corrected for the diamagnetic contribution using Pascal’s constants56. Experimental data were modeled with the julX program57 using a fitting procedure to the spin Hamiltonian –6 cm3 mol–1) and some weak intermolecular interactions (–0.12 K). The latter were considered in a mean field approach by using a Weiss temperature Θ58. The Weiss temperature Θ (defined as Θ = zJinterS(S + 1)/3k) relates to intermolecular interactions zJinter, where Jinter is the interaction parameter between two nearest neighbor magnetic centers, k is the Boltzmann constant (0.695 cm–1 K–1), and z is the number of nearest neighbors.Temperature-dependent magnetic susceptibility measurements for http://www.ccdc.cam.ac.uk/data_request/cif.The data that support the findings of this study are available from the corresponding author on reasonable request. The X-ray crystallographic coordinates for structures reported in this study have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition numbers 1567701–1567706. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via Supplementary Information(PDF 4825 kb)Peer Review File(PDF 139 kb)Description of Additional Supplementary Files(PDF 166 kb)Supplementary Data 1(XLSX 196 kb)


Scientific Reports7: Article number: 44813; 10.1038/srep44813 published online: 03202017; updated: 09202017.The original version of this Article contained typographical errors in the Abstract.6 (dielectric loss ~5 × 10−7) at high powers, degrading to 7 × 10−5  and g-factor of 1.995 ± 0.008”.“Whispering Gallery Mode (WGM) analysis revealed large Quality Factors of order 2 × 10now reads:6 (dielectric loss ~5 × 10−7) at high powers, degrading to 7 × 105 (dielectric loss ~1.4 × 10−6) at single photon energy. A very low-loss narrow line width paramagnetic spin flip transition was detected with extreme sensitivity in 28Si, with very small concentration below 1011 cm−3 (less than 10 parts per trillion) and g-factor of 1.995 ± 0.008”.“Whispering Gallery Mode (WGM) analysis revealed large Quality Factors of order 2 × 10This has now been corrected in the PDF and HTML versions of the Article.


II with the bridging ligand bis(pyridin-3-ylmethyl)sulfane afforded a one-dimensional zigzag chain polymeric structure, with the charge balanced by two coordinated chloride anions. C—H⋯Cl hydrogen bonds and Hg—Cl⋯π interactions, together with C—H⋯π hydrogen bonds, stabilize the crystal structure.The reaction of Hg L, C12H12N2S) in methanol afforded the title crystalline coordination polymer catena-poly[[dichloridomercury(II)]-μ-bis(pyridin-3-ylmethyl)sulfane-κ2N:N′], [HgCl2L]n. The asymmetric unit consists of one HgII cation, one L ligand and two chloride anions. Each HgII ion is coordinated by two pyridine N atoms from separate L ligands and two chloride anions. The metal adopts a highly distorted tetrahedral geometry, with bond angles about the central atom in the range 97.69 (12)–153.86 (7)°. Each L ligand bridges two HgII ions, forming an infinite –(Hg–L)n– zigzag chain along the b axis, with an Hg⋯Hg separation of 10.3997 (8) Å. In the crystal, adjacent chains are connected by intermolecular C—H⋯Cl hydrogen bonds, together with Hg—Cl⋯π interactions [chloride-to-centroid distance = 3.902 (3) Å], that form between a chloride anion and the one of the pyridine rings of L, generating a two-dimensional layer extending parallel to (101). These layers are further linked by intermolecular C—H⋯π hydrogen bonds, forming a three-dimensional supramolecular network.The reaction of mercury(II) chloride with bis(pyridin-3-ylmethyl)sulfane ( The flexibility, length and coordinating ability of the spacer ligands exert strong influences on the formation of coordination polymers and their resulting diverse topologies (Zheng L), and has reported its AgI and CoII coordination polymers  chloride with L sulfane sulfane, C12H12N2S. The asymmetric unit comprises one HgII cation, one L ligand and two chloride anions. The HgII ion is four-coordinated, binding to two Cl anions and two pyridine N atoms from two separate symmetry-related L ligands, forming a highly distorted tetrahedral geometry  Å. In the L ligand, the dihedral angle between the two terminal pyridine rings is 78.52 (18)°, and the flexible thioether moiety [C4–C6–S1–C7–C8] shows a bent arrangement with a gauche--anti configuration . The conformation of the L ligand, along with its Npy—Hg—Npy coordination angle [98.39 (16)°], may induce the zigzag topology of the chain.Fig. 1ry Fig. 1, with thry Fig. 1. The S aon Fig. 2. The sepet al., 2009L with Cl2⋯Cg1iv = 3.902 (3) Å and Hg1—Cl2⋯Cg1iv = 77.21 (6)° , generating layers extending parallel to (101). Neighboring layers are linked by C2—H2⋯Cg2 hydrogen bonds  gave three hits. Two   of the L ligand adopts a bent arrangement that is similar to that of the HgII polymer described here. However, the title compound displays a zigzag topology and is the first example of an HgII coordination polymer with the ligand L.A search of the Cambridge Structural Database  = 1.2Ueq(C).Crystal data, data collection and structure refinement details are summarized in Table 310.1107/S205698901701619X/sj5541sup1.cifCrystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S205698901701619X/sj5541Isup2.hklStructure factors: contains datablock(s) I. DOI: 1584773CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


E)-4-methoxybenzylideneamino]propan-2-ol, molecules are linked by O—H⋯N hydrogen bonds into C(5) supramolecular chains propagating along the a-axis direction.In the crystal of 1,3-bis[°. In the crystal, O—H⋯N hydrogen bonds link the molecules into infinite C(5) chains propagating along the a-axis direction. The packing of these chains is consolidated by C—H⋯O interactions and C—H⋯π short contacts, forming a three-dimensional network.The title Schiff base, C The N1=C1 and N2=C5 distances of 1.265 (4) and 1.271 (4) Å, respectively, are consistent with C=N double bonding. The bond angles of 117.0 (3) and 117.7 (3)° around the N1 and N2 atoms confirm their sp2 character. The slight differences between N=C distances and C—N=C angles are due to the significant effect of the hydrogen bond on the geometric parameters of the nitrogen atom (N2) involved in the intermolecular hydrogen bond (see below).The molecular structure of the title compound is illustrated in Fig. 1The N1—C2—C3—C4 torsion angle is −64.4 (4)° and the C2—C3—C4—N2 torsion angle is 175.0 (3)°. The O1—C3—C4—N2 torsion angle is −65.3 (3)°, which has a significant role to play in the hydrogen-bonding pattern in the crystal of the title compound (see below). The two methoxy substituents are essentially coplanar with their bound benzene rings with torsion angles C17—O2—C14—C13 = 169.3 (3)° and C27—O3—C24—C23 = −172.2 (3)°.C(5) chains extending along the a-axis direction. The chains are further linked to neighbouring chains through a pair of weak C—H⋯O hydrogen bonds (Table 1Cg (π–ring) interactions  = 0.95 Å for aromatic and azomethine atoms, d(C—H) = 0.99 Å for methylene, d(C—H) = 1.00 Å for C3—H3 and 0.98 Å for CH3 atoms. The Uiso values were constrained to be 1.5Ueq of the carrier atom for methyl H atoms and 1.2Ueq for the remaining H atoms. A rotating group model was used for the methyl groups. The absolute structure of the crystal chosen for data collection was indeterminate in the present refinement.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989016016947/hb7623sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989016016947/hb7623Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989016016947/hb7623Isup3.cmlSupporting information file. DOI: 1511139CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The synthesis and structural determination of a nickel(II) complex where the two nickel cations in the asymmetric unit each are coordinated by two tridentate, potentially redox non-innocent bis-iminopyridyl ligands are reported. N}ethyl)pyridine-κN]nickel(II) dichloride–dichloromethane–water (1/2/2), [Ni(C25H29N5)2]Cl2·2CH2Cl2·2H2O, represents a nickel(II) bis(pyridine diimine) complex with electron-donating dimethylaminophenyl substituents. The complex crystallizes as a water/dichloromethane solvate with Z′ = 2, thus the asymmetric unit consists of two NiII complex cations, four chloride anions, four adventitious water and four dichloromethane solvent molecules. Around each octahedrally coordinated NiII cation, one pendant phenyl group on each of the two ligands has an intramolecular π–π interaction with the pyridine ring of the other chelating ligand. In the crystal, pairs of water molecules are hydrogen bonded to pairs of chlorine atoms. The dichloromethane solvent molecules are likewise hydrogen bonded to the chloride anions.The solvated title compound, bisimino-κ A solution of 2,6-diacetylpyridine , 4-(dimethylamino)aniline  and formic acid (1 ml) was prepared in toluene (100 ml) under nitrogen atmosphere and then stirred for 12 h on molecular sieves. The reaction mixture was filtered and extracted with excess dichloromethane, then the amount of solvent was reduced in vacuo. The crude yellow product was then washed with cold methanol, followed by diethyl ether and filtered producing a pure bright-yellow solid . 1H NMR : δ 8.4–8.2 , 7.9–7.8 , 6.8  3.0 , 2.5 . MS (ESI): 400.4 m/z [C25H29N5]H+.Synthesis of [bis-ethyl)pyridine)nickel(II)] chloride. A solution of the PDI-DMA ligand  and nickel(II) chloride  was prepared in THF (15 ml) under nitrogen atmosphere, then stirred for 12 h. The solution was filtered and extracted with dichloromethane. The solvent was removed in vacuo yielding a dark reddish-brown solid . X-ray diffraction quality crystals were isolated as red–brown blocks by vapor diffusion of hexanes into a saturated solution of the product and dichloromethane. The complex was NMR silent (paramagnetic). MS (ESI): m/z 855.5 [C50H57N10Ni]+.Uiso(H) = 1.2 ×, 1.2 × or 1.5 × Ueq(C) for aromatic, methylene and methyl H atoms, successively. Water H atoms were initially located from a difference Fourier map and included in their initially observed positions and allowed to ride with the position of the parent oxygen atom. Displacement parameters of the hydrogen atom were freely refined. Two reflections  I. DOI: 10.1107/S2056989017010088/wm5402Isup2.hklStructure factors: contains datablock(s) I. DOI: 1560729CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


A combined single-crystal X-ray diffraction and NMR crystallography study of a 1:1 cocrystal of two fungicides, namely dithianon and pyrimethanil, is presented. Specifically, the role of hydrogen bonding and C—H⋯π and S⋯O intermolecular interactions is quantitatively investigated. H,10H-naphthodithiine-2,3-dicarbonitrile–4,6-dimethyl-N-phenylpyrimidin-2-amine (1/1), C14H4N2O2S2·C12H13N2]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental 1H and 13C chemical shifts are determined from two-dimensional 1H–13C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C—H connectivities and longer-range C⋯H proximities, whereas H⋯H proximities are identified in a 1H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated molecules allows the determination of the change in chemical shift upon going from an isolated molecule to the full crystal structure. For the 1H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to intermolecular N—H⋯O and C—H⋯O hydrogen bonding, while changes of −2.7 and −1.5 ppm are due to ring current effects associated with C—H⋯π interactions. Even though there is a close intermolecular S⋯O distance of 3.10 Å, it is of note that the molecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small.A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely dithianon (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5 While this is an established procedure in the development of new active pharmaceutical ingredients, where it is used to increase the solubility and bioavailability  NMR with calculation of NMR parameters, is finding important application to moderately sized organic molecules  were mixed thoroughly in a 1:1 molar ratio (0.5 g of pyrimethanil) and kept at 323 K under agitation. After a couple of hours, the powdery product had changed to a dark-olive-green colour.The DI–PM cocrystal was prepared according to method VII in point [0041] of Sowa  al. 2013, i.e. drUiso(H) = 1.2–1.5Ueq(parent)], after which the positions were refined with riding constraints  MAS experiments were performed on a Bruker Avance III spectrometer operating at 1H and 13C Larmor frequencies of 600 and 150.9 MHz, respectively, using a 1.3 mm HXY (1H MAS) or a 4 mm HX (13C CP MAS) Bruker probe. In all cases, a 1H 90° pulse duration of 2.5 µs was used. 2D 1H–13C HETCOR experiments were performed on a Bruker Avance III spectrometer, using a 4 mm HXY probe in double-resonance mode. In the HETCOR pulse sequence, the following phase cycling was employed: 1H 90° pulse (90° 270°), 13C 180° pulse (2{0°} 2{180°}), 13C CP contact pulse (4{0°} 4{180°} 4{90°} 4{270°}), receiver (0° 180° 0° 180° 180° 0° 180° 0° 90° 270° 90° 270° 270° 90° 270° 90°). For CP, a 70 to 100% ramp  were relaxed and periodic boundary conditions were applied. The space group P21/n was preserved. All distances and angles stated in the main text of this article are for the geometry-optimized crystal structure. Note also that the geometry optimization within CASTEP causes a relabelling of the atoms – in this article, we use the CASTEP numbering; see Fig. S1 in the Supporting information for a comparison with the numbering employed in the crystallographic CIF file. The GIPAW method , a chain of molecules is held together by N—H⋯O and C—H⋯O hydrogen bonds (between DI and PM molecules) and by putative S⋯O interactions  and 1(c), respectively. As can be seen from the representation along the crystallographic a axis in Fig. 1c), the packing is based on assemblies of blocks of four molecules; four molecules (PM–DI–DI–PM) are arranged in a layer , forming a block that is perpendicular to an adjacent block of four molecules, thus building up the ‘zigzag’ arrangement.The single-crystal X-ray diffraction structure of the DI–PM cocrystal is schematically represented in Fig. 1er Fig. 1a, formi13C CP MAS NMR 1D spectrum  of the DI–PM cocrystal, together with three stick spectra  that represent 13C chemical shifts calculated using the GIPAW method for the DI–PM crystal structure. Specifically, the calculated 13C chemical shifts are presented in three groups according to whether they correspond to direct one-bond C—H connectivities  or nonprotonated C atoms . The distinction between Figs. 2c) and 2(d) corresponds to whether cross peaks corresponding to a longer-range C⋯H proximity are observed in 1H–13C 2D correlation spectra  and 3(b) present 1H NMR spectra of the DI–PM cocrystal recorded at a fast MAS frequency of 60 kHz; specifically, a one-pulse one-dimensional spectrum in Fig. 3a), together with vertical lines corresponding to calculated (GIPAW) 1H chemical shifts, as well as a 2D DQ spectrum in Fig. 3b). In addition, Fig. 3c) presents a 1H–13C 2D correlation spectrum of the DI–PM cocrystal; note that this spectrum has been rotated through 90° from its usual representation such that the direct (13C) dimension is vertical. In this way, it is possible to directly compare  1H chemical shifts of peaks in the 1H–13C  and 1H DQ 2D  and 1H 1D  spectra. Two separate spectral regions are presented in Fig. 3c) corresponding to (top) the methyl resonances at a 13C chemical shift close to 25 ppm and (bottom) the aromatic CH resonances with 13C chemical shifts between 110 and 140 ppm.Figs. 33C Fig. 3c and 1H2D Fig. 3b and 1H1D Fig. 3a spectr1H–13C correlation spectrum in Fig. 3c) was recorded using a short CP contact time of 100 µs to transfer magnetization from 1H to 13C, such that cross peaks correspond to one-bond C—H connectivities. The spreading of the resonances into two dimensions in Fig. 3c) allows the identification of two and ten resolved cross peaks for the CH3 and aromatic CH groups, respectively. The value of such a 1H–13C correlation spectrum in resolving and assigning the experimental 1H chemical shifts is thus evident. Table 213C chemical shifts . For directly bonded C—H connectivities, H-atom labels and calculated (GIPAW) and experimental 1H chemical shifts are presented in normal font.The 1H–13C correlation spectra recorded with three different CP contact times of 100 µs , 500 µs  and 1 ms ; Fig. 4a) is a copy of Fig. 3c), but presented in the normal orientation, i.e. with the direct (13C) dimension horizontal. It is evident that additional cross peaks are observed for longer CP contact times – these correspond to longer-range C⋯H proximities , 160.1 (atom C63) and 168.2 ppm (atoms C64 and C67); these all correspond to intramolecular proximities within the dithianon molecule, i.e. C57 with H17 , H21  and H29 , C63 with H29 , C64 and C67 with H25  and CH3 protons . Of most interest is the  cross peak, which thus enables the determination of the NH 1H chemical shift.Fig. 4µs Fig. 4a, 500 µµs Fig. 4b and 1 ms Fig. 4c; Fig. 1H chemical shifts assigned, let us re-examine the 1H DQ MAS spectrum in Fig. 3b). In such a spectrum, cross peaks are observed in the DQ dimension at the sum of the two single-quantum (SQ) frequencies if there is a close proximity . Consider the two lowest-ppm aromatic CH protons H25 (4.0 ppm) and H2 (6.2 ppm) for which distinct 1H resonances are resolved in the 1H SQ dimension. For H25, the only DQ peak is at 4.0 + 2.0 = 6.0 ppm with the CH3 protons, since H25 is sandwiched between two methyl-group substituents on the PM molecule. For H2, there is a DQ peak at 6.2 + 7.5 = 13.7 ppm corresponding to the intramolecular H⋯H proximity with the neighbouring H1  and H3  DI aromatic CH protons, as well as a DQ peak at 6.2 + 2.0 = 8.2 ppm due to intermolecular proximities to the PM CH3 H atoms . Considering the high-ppm region, DQ cross peaks for the overlapping PI NH H29 (9.1 ppm) and aromatic CH H17 (9.1 ppm) resonances are observed at 9.1 + 7.7 = 16.8 ppm for intramolecular H29⋯H21 (2.21 Å) and H17⋯H18 (2.50 Å) proximities, as well as at 9.1 + 2.0 = 11.1 ppm for intermolecular proximities to PM methyl-group protons (closest distances of H17⋯H26 = 2.48 Å and H29⋯H24 = 2.64 Å). For the other overlapping CH aromatic resonances, cross peaks due to intramolecular proximities with other CH aromatic resonances, as well as intermolecular proximities to the methyl protons, are also observed.With all the 1H–13C correlation spectra presented in Fig. 413C and 1H chemical shifts. Specifically, in Fig. 4a), red crosses correspond to direct C—H one-bond connectivities (C—H distances under 1.2 Å), while in Figs. 4b) and 4(c), red crosses are presented for C—H proximities between 1.2 and 2.2 Å , and between 2.2 and 3.0 Å . We comment here on the level of agreement between experimental and calculated (GIPAW) chemical shifts. Starting with a consideration of the aromatic CH moieties ; this corresponds to the established observation that the discrepancy is within 1% of the chemical shift range . For the 1H chemical shifts, while most are within the usual 0.3 ppm, some exhibit slightly larger discrepancies, notably 0.6 ppm for atoms H17 and H25.In the  Å Fig. 4b, and b Å Fig. 4c. We co3 groups , whereas the calculated 13C chemical shifts are both 8.5 ppm lower than the experimental values, although the experimental difference in 13C chemical shifts between atoms C65 and C68 of 1.8 ppm is reproduced by the calculation (difference of 1.9 ppm). The explanation for this is well known, namely, the gradient of a plot of experimental 13C chemical shifts against calculated shielding deviates slightly from −1 , where the calculated 1H chemical shift of 10.5 ppm is 1.4 ppm higher than the experimental value of 9.1 ppm. Such a large difference is explained by a known temperature dependence  for hydrogen-bonded protons  atom that is involved in an intermolecular N—H⋯O hydrogen bond to atom O1 . Interestingly, Δδcrystal–molecule = 2.0 ppm for the aromatic CH H21 atom, for which Fig. 1a) identifies an intermolecular C—H⋯O so-called weak hydrogen-bonding  and H2 (−1.6 ppm); as shown in Fig. 51H chemical shift are a consequence of ring current effects associated with the proton pointing towards the centre of a six-membered aromatic ring of a nearby PM molecule in a C—H⋯π interaction, as has been noted previously in a number of other cases   global, I. DOI: 10.1107/S2053229617000870/df3006Isup3.hklStructure factors: contains datablock(s) I. DOI: 10.1107/S2053229617000870/df3006sup2.txtCASTEP cif output. DOI: 10.1107/S2053229617000870/df3006sup4.txtmagres file. DOI: 10.1107/S2053229617000870/df3006sup5.pdfAdditional Tables  13C chemical shift values) and a Figure showing the difference in the numbering schemes between the crystallographic data and the output of the GIPAW (CASTEP) calculations. DOI: 1507863CCDC reference:


Podanthus mitiqui, is reported and the stereochemical features established.The structure of erioflorin, a germacrane sesquiterpene lactone isolated from  19H24O6 cyclodecafuran-9-yl methacrylate], is a tricyclic germacrane sesquiterpene lactone, which was isolated from Podanthus mitiqui (L.). The compound crystallizes in the space group P212121, and its molecular structure consists of a methacrylic ester of a ten-membered ring sesquiterpenoid annelated with an epoxide and a butyrolactone. The structure is stabilized by one intramolecular C—H⋯O hydrogen bond. An O—H⋯O hydrogen bond and further C—H⋯O interactions can be observed in the packing.The title compound, erioflorin, C Podanthus mitiqui (Lindl)  is an endemic plant of the Central Zone of Chile. It is an evergreen shrub that can reach up to two meters in height; its flowers are yellow or orange–yellow globose inflorescences. Previous chemical investigations of extracts isolated from the stems and leaves of Podanthus mitiqui revealed the presence of sesquiterpene lactones with a germacrane framework such as ovatifolin, deacetylovatifolin and arturin  Å and smallest displacement parameters φ of 23.2 (8), 252.2 (3) and 346.1 (2)°. The maximum deviation from the mean plane is 0.589 (3) Å (C3). The C—C bond lengths range from 1.474 (5) to 1.557 (4) Å. The Z-configured double bond is located between C4 and C5 with a bond length of 1.326 (4) Å. Some bond angles differ notably from ideal values due to the ring strain, such as C3—C4—C5 and C4—C5—C6 . The bond angles within the ten-membered ring including Csp3 atoms range from 112.0 (3)° to 125.7 (3)°. The ten-membered and the five-membered rings are trans-fused. The lactone ring shows a closed puckering on C6-C7 (twisted). The puckering amplitude and the smallest displacement parameter of the five-membered ring are q = 0.192 (3) Å and φ = 58.7 (9)°. With respect to the lactone ring, H6 and H7 are equatorially oriented, whereas the C6—C5 and the C7—C8 bonds are axial. The maximum deviations of the substituents from the best plane are 0.065 (6) Å (O4) and −0.323 (6) Å (C13). The 1,10-epoxy ring is trans-fused. The C8 side chain is β oriented as well as the C10 methyl group, whereas the C4 methyl group is α. The methacrylate substituent deviates from the planarity by twisting about C16—C17 [torsion angle O5—C16—C17—C19 = 28.4 (5)°]. The structure is closely related to that of dihydroheliangine monochlorido acetate , eriophyllin-B  and eriophyllin-C , which were also isolated from Eriophyllum confertiflorum  to 0.805 (3) Å, yielding a total puckering amplitude ii, running along the c-axis direction is formed via the hydroxyl group and the lactone oxo group , approximately between the a and b axes (C7—H7⋯O1i) and along b (C13—H13B⋯O6iii). Non-hydrogen intermolecular contacts are found between O2 and O4iv . The unit cell contains no residual solvent-accessible voids.The crystal structure features infinite chains connected by hydrogen bonds. A strong O—H⋯O hydrogen bond, namely O2—H2⋯O4up Fig. 2. Furtheret al. . Aerial parts (9.6 kg) were powdered and extracted by maceration with ethyl acetate for 3 d. The organic layer was evaporated in vacuo giving a crude product (250 g) which was further purified by column chromatography, giving a primary fractioning of 11 fractions (F1–F11) by using increasing polarity from hexane to ethyl acetate. F-8 (6 g) was further purified by column chromatography  giving a white solid, which was recrystallized from EtOc, affording colourless crystals suitable for X-ray diffraction analysis. M.p. (from methanol): 499–500 K. For further physical data  for erioflorin, see Torrance et al. , C—H = 0.98 Å (–CH2), C—H = 0.99 Å, (–CH), C—H = 0.94 Å (=CH2), and Uiso(H) = 1.5Ueq(CH3) and Uiso(H) = 1.2Uiso, with the exception of the O—H hydrogen atom, which was refined freely, but with Uiso(H) = 1.5Uiso(O).Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989017001700/zl2693sup1.cifCrystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989017001700/zl2693Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017001700/zl2693Isup3.cmlSupporting information file. DOI: 1530526CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


As a result of the presence of these ordered species, the framework changes its symmetry from P4/mmm to P21/c. The 4,4′-bipyridine guest molecules form chains inside the 6.5 × 6.9 Å pores parallel to [100] in which the molecules interact through π–π stacking. Ordered water molecules form infinite hydrogen-bonded chains inside a second pore system (1.6 × 5.3 Å free aperture) perpendicular to the 4,4′-bipyridine channels.The coordination polymer {[Cu(SiF These interconnected pores are filled with two other 4,4′-bipyridine molecules and five water molecules  and this may be related to the fact that, in the present compound, guest molecules fill the pores and interact significantly with the framework atoms (see below).The 2D coordination grids are stacked along the [100] direction through the SiFs Figs. 3 and 4 ▸.62− show some variations : 45.29 (7)°; bipy(N37–N43): 30.31 (7)°]. Whereas the 4,4′-bipyridine molecules belonging to the coordination network are rather rigid between the metal atoms , the adsorbed 4,4′-bipyridine molecules display significantly larger atomic displacement parameters [Ueq = 0.025 (5) Å2].Four of the five water molecules (O49 to O52) form infinite es Fig. 5. The fifes Fig. 5. The 4,4es Fig. 5, and arees Fig. 5; these iet al., 20166)(C10H8N2)2]n coordination polymer framework [CSD refcodes: GORWUF 2]·8H2O}n undergoes a structural conversion when immersed in water, leading to an interpenetrated network where SiF62− anions are shifted out of the coordination sphere of copper ions and are replaced by water molecules [CSD refcodes: AFEHOI  of hydrated copper(II) tetrafluoridoborate  was added to a refluxing acetonitrile solution (5 cm3) of 4,4′-bipyridine . After filtration, Et2O vapor was diffused into the mother liquor for seven days, and then the solvent was allowed to evaporate very slowly. A mixture of blue and violet crystals was obtained; whereas the diffraction spots of the blue crystals could not be properly indexed, the violet crystals were of very good quality and led to the structure reported on herein.An aqueous solution (5 cmUiso(H) = 1.2Uiso(C).Crystal data, data collection and structure refinement details are summarized in Table 410.1107/S2056989016016686/vn2118sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989016016686/vn2118Isup2.hklStructure factors: contains datablock(s) I. DOI: 1510381CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information:


S(5) ring motif. In the crystals of both compounds, molecules are linked by pairs of N—H⋯S hydrogen bonds, forming dimers with In the title compounds, the thiosemicarbazone group adopts an extended conformation, and there is a short N—H⋯N contact present forming an  11H13N3O2S, (I), and C16H15N3O2S, (II), the thiosemicarbazone group adopts an extended conformation. The acetate ester (I) crystallizes with two independent molecules in the asymmetric unit. In the benzoate ester (II), the planes of the two aryl rings are inclined to one another by 46.70 (7)°. In both compounds, there is a short intramolecular N—H⋯N contact present, forming an S(5) ring motif. In the crystals of both compounds, molecules are linked via pairs of N—H⋯S hydrogen bonds, forming dimers with R22(8) ring motifs. The dimers are linked by N—H⋯S and N—H⋯O hydrogen bonds, forming slabs parallel to (01-1). In (I), there are N—H⋯π and C—H⋯π interactions present within the slabs, while in (II), there are only N—H⋯π interactions present.In the title compounds, C They display antiproliferative activity on different tumors cell lines and have been a common feature of all compounds with carcinogenic potency. A strong correlation has been found between tumor growth rate and the ribonucleoside diphosphate reductase (RDR) enzyme  ring motif ° in molecule B of compound (I)] and S1—C16—N2—N1 [172.2 (1)° in compound (II)]. In compound (I)A and B, respectively]. The bond lengths C11A—S1A [1.692 (2) Å] and C11B—S1B [1.680 (2) Å] in (I)et al., 2016syn-periplanar to C5 [C5—C6—C7—O1 = −15.8 (2) °] and anti-periplanar to C1 [C1—C6—C7—O1 = 160.7 (1) °]. The dihedral angle between the benzene rings in compound (II)The molecular structure of compounds (I)f Figs. 1 and 2 ▸.A–B dimers with an In the crystal of (I)In the crystal of (II)f Table 2. As in tet al., 2016E)-4-(N-carbamothioylethanehydrazonoyl)phenyl 4-methylbenzoate : Thiosemicarbazide  was added to 50 ml of an ethanolic solution of the 4-acetyl phenyl acetate (0.01 mol) for (I)Uiso(H) = 1.5Ueq(C-methyl) and 1.2Ueq for other H atoms.Crystal data, data collection and structure refinement details are summarized in Table 310.1107/S2056989016018983/su5323sup1.cifCrystal structure: contains datablock(s) global, I, II. DOI: 10.1107/S2056989016018983/su5323Isup2.hklStructure factors: contains datablock(s) I. DOI: 10.1107/S2056989016018983/su5323IIsup3.hklStructure factors: contains datablock(s) II. DOI: 1519492, 1519491CCDC references:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


S(6) ring motif. In the crystal, molecules are linked by N—H⋯N and C—H⋯N hydrogen bonds forming chains propagating along the a-axis direction.The title isonicotinohydrazide derivative is planar, with an r.m.s. deviation for the fitted non-H atoms of 0.062 Å, and an intramolecular O—H⋯N hydrogen bond with an  13H10FN3O2, the molecule has an E conformation with respect to the C=N bond of the hydrazone bridge. The dihedral angle between the isonicotinoyl and fluorophenol moieties is 4.03 (4)°, and an intramolecular O—H⋯N hydrogen bond generates an S(6) ring motif. In the crystal, molecules are linked by N—H⋯N and C—H⋯N hydrogen bonds, forming chains propagating along the a-axis direction. The chains are linked by C—H⋯O hydrogen bonds, resulting in the formation of layers lying parallel to the ab plane. The crystal structure also features π–π interactions [centroid-to-centroid distance = 3.6887 (8) Å].In the title compound, C The C6—N2 and C7—N3 bond lengths differ by 0.08 Å hence; these two bonds are formally double and single bonds, respectively. The molecule deviates slightly from planarity with an r.m.s deviation for the fitted non-hydrogen atoms of 0.062 Å. There is an intramolecular O2—H2O⋯N3 hydrogen bond with an S(6) ring motif present in the pyridine carboxamide moiety, and the pyridine ring (N1/C1–C5) is approximately coplanar with the amide group (C6(=O1)N2) [dihedral angle = 8.25 (6)°]. The isonicotinoyl moiety (N1/C1–C6/O1/N2) is inclined to the fluorophenol moiety (C8-C13/O2/F1) by 4.03 (4)°.The molecular structure of the title compound, with atom labelling, is presented in Fig. 1N⋯N1i and C4—H4⋯N1i hydrogen bonds  Å; Cg1 and Cg2 are the centroids of the pyridine (N1/C1–C5) and phenyl (C8–C13) rings, respectively; symmetry code: (i) −x + 1, −y + 1, −z + 1].In the crystal, molecules are linked by bifurcated-acceptor N2—H2s Table 1, leadinget al., 2016E)-N-(2-hydroxybenzylidene)isonicotinohydrazide skeleton revealed 86 hits. They include the isotypic crystal structures with bromide  d 6.94 , 7.32 , 7.44 , 7.85 , 8.70 , 8.81 , 11.40 , 12.39 . HR–MS (ES+) C13H11FN3O2 requires 260.0835 [M + H]+; found 260.0830.Isonicotinic acid hydrazide  and 3-fluorosalicylaldehyde  were suspended in a 1:1 mixture of water and ethanol (6 ml). The reaction mixture was stirred at 363 K for 24 h and formation of a precipitate was observed. The reaction mixture was allowed to cool to room temperature and then filtered. The isolated solid was washed with water to give the product as a white solid . Colourless rod-like crystals, suitable for X-ray diffraction analysis, were grown by slow evaporation of a solution in methanol of the title compound. Uiso(H) = 1.5Ueq(O) and 1.2Ueq for other H atoms.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989017009926/su5379sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989017009926/su5379Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017009926/su5379Isup3.cdxSupporting information file. DOI: Click here for additional data file.10.1107/S2056989017009926/su5379Isup4.cmlSupporting information file. DOI: 1560196CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information: