Jamshid Ashurov

2-Methyl­pyridine–urea (1/1)

In the crystal structure of the title compound, C6H7N·CH4N2O, the 2-methylpyridine and urea molecules are linked via N—H⋯O and N—H⋯N hydrogen bonds, forming ribbons extending along the a axis. The dihedral angle between the 2-methylpyridine and urea mean planes is 89.09 (9)°. The methyl group shows rotational disorder wherein the H atoms are located over two sets of sites with equal occupancies.

Tetra­aqua­bis­[2-(2-oxo-2,3-dihydro-1,3-benzoxazol-3-yl)acetato]­zinc

The ZnII ion in the title compound, [Zn(C9H6NO4)2(H2O)4], is located on an inversion center and is octahedrally coordinated by two 2-(2-oxo-2,3-dihydro-1,3-benzoxazol-3-yl)acetate anions in axial sites and four water molecules in equatorial positions. In the crystal, O—H⋯O hydrogen bonds between the coordinated water molecules and carbonyl–carboxylate O atoms lead to pleated sheets parallel to (001).

Conformational dimorphism in o-nitrobenzoic acid: alternative ways to avoid the O...O clash.

Polymorphism is a challenging phenomenon and the competitive packing alternatives which are characteristic for polymorphs may be encountered for essentially rigid molecules. A second crystal form of the well known compound o-nitrobenzoic acid, C7H5NO4, an important intermediate in the production of dyes, pharmaceuticals and agrochemicals, is described. Although obtained serendipitously, its intra- and intermolecular features match expectations from database searches and theoretical calculations. O-H...O hydrogen-bonded carboxylic acid dimers represent the building blocks in both polymorphs. For steric reasons and in agreement with a calculated potential energy surface, the carboxylic acid and nitro groups cannot simultaneously be coplanar with the benzene ring but have to tilt. In the well established crystal form, this out-of-plane torsion is more pronounced for the nitro substituent. In contrast, the new polymorph is characterized by a major tilt of the carboxylic acid group. The molecules in both alternative crystal forms achieve a similar compromise with respect to acceptable intramolecular O...O contacts.

Complexes of acetic acid α-(N-benzoxazolin-2-one) with Zn(II), Cu(II), and Co(II): Syntheses and crystal structures

The results of syntheses and X-ray diffraction analyses of mononuclear complexes [ML2(H2O)4] (M = Co2+(I), Cu2+(II), and Zn2+(III)) containing water molecules and anions of acetic acid α-(N-benzoxazolin-2-one) (L = C9H6O4) are presented. The crystals of complexes I–III are isostructural (space group P21/n, Z = 2) and are built of discrete neutral complex molecules. The crystallographic data are as follows: for complex I, a = 6.1470(5), b = 5.3310(3), c = 30.5894(17) Å, β = 95.056(6)°, V = 998.50(11) Å3; for complex II, a = 5.9661(6) Å, b = 5.1414(4) Å, c = 32.672(2) Å, β = 92.395(6)°, V = 1001.33(14) Å3; and for complex III, a = 6.1404(3) Å, b = 5.3476(2) Å, c = 30.5865(12) Å, β = 94.708(4)°, V = 1000.96(7) Å3. The metal atoms (M) of the complexing agents are localized in the crystallographic symmetry centers and have a distorted octahedral environment due to two oxygen atoms of the carboxy groups of two monodentate ligands (L) and four water molecules. The M-O(1w)(H2O) and M-O(2w)(H2O) bond lengths for the indicated complexes are 2.088(3) and 2.118(3), 2.446(3) and 1.971(3), and 2.113(4) and 2.093(3) Å for M = Co2+, Cu2+, and Zn2+, respectively. The crystal structures are formed due to packing of chains built of inter-molecular hydrogen bonds O-H…O.

Bis(acetyl­acetonato-κ2O,O′)(2-amino-1-methyl-1H-benzimidazole-κN3)oxido­vanadium(IV)

The title mixed-ligand oxidovanadium(IV) compound, [VO(C5H7O2)2(C8H9N3)], contains a VIV atom in a distorted octahedral coordination, which is typical for such complexes. The vanadyl group and the N-heterocyclic ligand are cis to each other. The coordination bond is located at the endocyclic N atom of the benzimidazole ligand. Intramolecular hydrogen bonds between the exo-NH2 group H atoms and acetylacetonate O atoms stabilize the crystal structure.

X-Ray Structures of Three Polymeric and Two Mononuclear Metal Complexes on the Base of p-Aminobenzoic Acid

Crystals of five coordination compounds have been grown from solutions containing p-aminobenzoic acid (PABA), diethanolamine (DEA) and salt of the definite metal. The X-ray crystallography attests that complexes [Co(PABA)2(H2O)2]n·H2O (1), [Ni(PABA)2(H2O)2]n·H2O (1′) and [Zn(PABA)2(H2O)]n·H2O (2) are polymeric, while Mn(DEA)2·2(PABA)·2(H2O) (3) and Cr(DEA)2·2(PABA) (4) are mononuclear coordination compounds. In the isomorphic polymers 1 and 1′ metal ions are bridged to infinite columns by coordination bonds of the two antiparallel PABA molecules (bimolecular association). The complex 2 is 2-D polymer repeating units of which are hexagons generated by combination of mono- and bimolecular associations. All six coordination sites of Mn2+- and Cr2+-ions in 3 and 4 are occupied by two DEA molecules retaining PABA anions in outer sphere. The CSD analysis shows that there are five types of coordination polymers bridged by O and N atoms of the PABA-molecules. As a result of this research two new type motif polymers have been added to the existing list.Graphical Abstract

Crystal structure of trans-bis­(di­ethano­lamine-κ3O,N,O′)manganese(II) bis­(3-amino­benzoate)

The title salt, [Mn(C4H11NO2)2](C7H6NO2)2, contains a centrosymmetric cation with the Mn2+ ion coordinated octahedrally by two tridentate diethanolamine (DEA) ligands. The cations are connected to the anions through O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional network structure.

Charge density of the biologically active molecule (2-oxo-1,3-benzoxazol-3(2H)-yl)acetic acid

(2-Oxo-1,3-benzoxazol-3(2H)-yl)acetic acid is a member of a biologically active class of compounds. Its molecular structure in the crystal has been determined by X-ray diffraction, and its gas phase structure was obtained by quantum chemical calculations at the B3LYP/6-311++G(d,p) level of theory. In order to understand the dynamics of the molecule, two presumably soft degrees of freedom associated with the relative orientation of the planar benzoxazolone system and its substituent at the N atom were varied systematically. Five conformers have been identified as local minima on the resulting two-dimensional potential energy surface within an energy window of 27 kJ mol(-1). The energetically most favourable minimum closely matches the conformation observed in the crystal. Based on high-resolution diffraction data collected at low temperature, the experimental electron density of the compound was determined. Comparison with the electron density established by theory for the isolated molecule allowed the effect of intermolecular interactions to be addressed, in particular a moderately strong O-H...O hydrogen bond with a donor...acceptor distance of 2.6177 (9) Å: the oxygen acceptor is clearly polarized in the extended solid. The hydrogen bond connects consecutive molecules to chains, and the pronounced charge separation leads to stacking between neighburs with antiparallel dipole moments perpendicular to the chain direction.

trans-Tetra­aqua­bis­[2-(4-chloro­phen­oxy)acetato-κO1]nickel(II)

In the title compound, [Ni(C8H6ClO3)2(H2O)4], the NiII ion is located on a crystallographic inversion centre and is octahedrally coordinated by two 2-(4-chlorophenoxy)acetate ligands in axial positions and by four water molecules in the equatorial plane. The acetate ligands are bound to the NiII ion in a monodentate manner through a carboxylate O atom. In the crystal, O—H⋯O hydrogen bonds link the molecules, forming a two-dimensional supramolecular network lying parallel to the ab plane.

A new polymorph of N-phenyl-phthalimide.

During an attempt to prepare a cocrystal of N-phenylphthalimide, C14H9NO2, with N-(2,3,4,5,6-pentafluorophenyl)phthalimide, a new orthorhombic polymorph of the first component was obtained. This new form has Z′ = 0.5 and the molecule is located around a twofold axis, whereas in the previously reported polymorph (space group Pbca), the molecule has no crystallographically imposed symmetry. Pairs of C—H⋯O interactions between inversion-related phthalimide units arrange molecules into tapes that are further assembled into (010) layers via stacking interactions between phthalimide fragments [interplanar distance = 3.37 (5) Å].