Notes

The Pyrazinacenes.
A novel one-dimensional zigzag chain-like CoII coordination polymer constructed from 4,4'-bi-pyridine (4,4'-bpy) and 2-hy-droxy-benzoate (2-OHbenz) ligands, namely, catena-poly[[(4,4'-bi-pyridine-κN)-(μ-2-hy-droxy-benzoato-κ2OO')(2-hy-droxy-benzoato-κ2O,O')cobalt(II)]-μ-4,4'-bi-pyridine-κ2NN'-[aquahemi(μ-4,4'-bi-pyridine-κ2NN')(2-hy-droxy-benzoato-κO(2-hy-droxy-benzoato-κ2OO')cobalt(II)], [Co2(C7H5O3)4(C10H8N2)2.5(H2O)] n , has been synthesized by reacting cobalt(II) nitrate trihydrate, 4,4'-bpy and 2-hy-droxy-benzoic acid in a mixture of water and methanol at room temperature. There are two independent CoII centers, Co1 and Co2, in the asymmetric unit, revealing a distorted octa-hedral geometry with chromophore types of [CoN2O4] and [CoN2O3O'], respectively. The Co1 ions are doubly bridged by 2-OHbenz ligands with syn-anti coordination mode, generating a dinuclear unit. The bridging 4,4'-bpy ligands connect these dinuclear units and the mononuclear Co2 chromophores, providing a one-dimensional alternating zigzag chain-like structure. In the crystal, inter-molecular hydrogen bonds, C-H⋯π and π-π stacking inter-actions are observed and these help to consolidate the packing. In addition, the physical properties of the title compound are reported.The asymmetric unit of the title compound, C11H12N2O2·H2O, contains a mol-ecule of 1,4,6-trimethyl-1,4-di-hydro-quinoxaline-2,3-dione and a solvent water mol-ecule. Four atoms of the benzene ring are disordered over two sets of sites in a 0.706 (7)0.294 (7) ratio while the N-bound methyl groups are rotationally disordered with occupancy ratios of 0.78 (4)0.22 (4) and 0.76 (5)0.24 (5). In the crystal, mol-ecules are linked by O-H⋯O and C-H⋯O hydrogen bonds into layers lying parallel to (10). Rapamycin in vivo The Hirshfeld surface analysis indicates that the most important contributions to the packing arrangement are due to H⋯H (51.3%) and O⋯H/H⋯O (28.6%) inter-actions. The mol-ecular structure calculated by density functional theory is compared with the experimentally determined mol-ecular structure, and the HOMO-LUMO energy gap has been calculated.The stabilized conformation of the title compound, C13H9Cl2N3O2, is similar to that of the isomeric compound (E)-1-(2,6-di-chloro-phen-yl)-2-(2-nitro-benzyl-idene)hydrazine. The 2,6-di-chloro-phenyl ring and the nitro-substituted benzene ring form a dihedral angle of 26.25 (16)°. In the crystal, face-to-face π-π stacking inter-actions along the a-axis direction occur between the centroids of the 2,6-di-chloro-phenyl ring and the nitro-substituted benzene ring. The mol-ecules are further linked by C-H⋯O contacts and N-H⋯O and C-H⋯Cl hydrogen bonds, forming pairs of hydrogen-bonded mol-ecular layers parallel to (100). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (22.1%), Cl⋯H/H⋯Cl (20.5%), O⋯H/H⋯O (19.7%), C⋯C (11.1%) and C⋯H/H⋯C (8.3%) inter-actions.The title phosphanegold(I) thiol-ate, C26H22AuFNOPS or [Au(C8H7FNOS)(C18H15P)], has the AuI centre coordinated by phosphane-P [2.2494 (8) Å] and thiol-ate-S [2.3007 (8) Å] atoms to define a close to linear geometry [P-Au-S = 176.10 (3)°]. The thiol-ate ligand is orientated so that the meth-oxy-O atom is directed towards the Au atom, forming an Au⋯O close contact of 2.986 (2) Å. In the crystal, a variety of inter-molecular contacts are discerned with fluoro-benzene-C-H⋯O(meth-oxy) and phenyl-C-H⋯F inter-actions leading to dimeric aggregates. These are assembled into a three-dimensional architecture by phenyl-C-H⋯S(thiol-ate) and phenyl-C-H⋯π(fluorobenzene, phen-yl) inter-actions. Accordingly, the analysis of the calculated Hirshfeld surface shows 30.8% of all contacts are of the type C⋯H/H⋯C but this is less than the H⋯H contacts, at 44.9%. Other significant contributions to the surface come from H⋯F/F⋯H [8.1%], H⋯S/S⋯H [6.9%] and H⋯O/O⋯H [3.2%] contacts. Two major stabilization energies have contributions from the phenyl-C-H⋯π(fluoro-benzene) and fluoro-benzene-C-H⋯C(imine) inter-actions (-37.2 kcal mol-1), and from the fluoro-benzene-C-H⋯F and phenyl-C-H⋯O inter-actions (-34.9 kcal mol-1), the latter leading to the dimeric aggregate.In the title mol-ecular salt, (C5H7N2)2[SnCl6], the cation is protonated at the pyridine N atom and the complete dianion is generated by a crystallographic centre of symmetry. In the crystal, N-H⋯Cl hydrogen bonds link the components into a three-dimensional network built up from the stacking of alternate cationic and anionic layers. The nature of the inter-molecular inter-actions has been analysed in terms of the Hirshfeld surfaces of the cations and the anions. The thermal behaviour and the Raman spectrum of the title compound are reported.Poly[(μ4-3-carboxybenzenesulfonato)silver(I)], Ag(O3SC6H4CO2H) or [Ag(C7H5O5S)] n , has been found to undergo a reversible phase transition from monoclinic to triclinic between 160 and 150 K. The low-temperature triclinic structure (space group P ) has been determined at 100 K. In contrast to the reported room temperature monoclinic structure, in which the nearly equivalent carboxyl-ate C-O distances indicate that the acidic hydrogen is randomly distributed between the O atoms, at 100 K the C-O (protonated) and C=O (unprotonated) bonds are clearly resolved, resulting in the reduction in symmetry from C2/c to P .In the title compound, C24H15Cl2N3O2, one quinoline ring system is essentially planar and the other is slightly bent. An intra-molecular O-H⋯N hydrogen bond involving the hy-droxy group and a pyridine N atom forms an S(5) ring motif. In the crystal, two mol-ecules are associated into an inversion dimer with two R22(7) ring motifs through inter-molecular O-H⋯N and O-H⋯O hydrogen bonds. The dimers are further linked by an inter-molecular C-H⋯O hydrogen bond and four C-H⋯π inter-actions, forming a two-dimensional network parallel to (001).The structure determination of [Fe(C13H15BN5)2] was undertaken as part of a project on the modification of the recently published spin-crossover (SCO) complex [FeH2B(pz)(pypz)2] (pz = pyrazole, pypz = pyridyl-pyrazole). To this end, a new ligand was synthesized in which two additional methyl groups are present. Its reaction with iron tri-fluoro-methane-sulfonate led to a pure sample of the title compound, as proven by X-ray powder diffraction. The asymmetric unit consists of one complex mol-ecule in a general position. The FeII atom is coordinated by two tridentate N-binding H2B(3,5-(CH3)2-pz)(pypz)- ligands. The Fe-N bond lengths range between 2.1222 (13) and 2.3255 (15) Å, compatible with FeII in the high-spin state, which was also confirmed by magnetic measurements. Other than a very weak C-H⋯N non-classical hydrogen bond linking individual mol-ecules into rows extending parallel to [010], there are no remarkable inter-molecular inter-actions.
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