Crystal structure and DFT study of (E)-2,6-di-tert-butyl-4-{[2-(pyridin-2-yl)hydrazin-1-yl-idene)meth-yl}phenol.

The title compound, C20H27N3O, was synthesized by condensation reaction of 3,5-di-tert-butyl-4-hy-droxy-benzaldehyde and 2-hydrazinyl-pyridine, and crystallizes in the centrosymmetric monoclinic space group C2/c. The conformation about the C=N bond is E. The dihedral angle between the rings is 18.1 (3)°. An inter-molecular N-H⋯N hydrogen bond generates an R22(8) ring motif. In the crystal, N-H⋯N hydrogen bonds connect pairs of mol-ecules, forming dimers. Density functional theory (DFT) optimized structures at the B3LYP/6-311 G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state.

Crystal structure and DFT study of 8-hy-droxy-1,2,3,5,6,7-hexa-hydro-pyrido[3,2,1-ij]quinoline-9-carbaldehyde.

In the title compound, C13H15NO2, the fused non-aromatic rings of the julolidine moiety adopt envelope conformations. The hy-droxy group forms an intra-molecular hydrogen bond to the aldehyde O atom, generating an S(6) ring motif. Weak inter-molecular C-H⋯O hydrogen bonds help to stabilize the crystal structure. Density functional theory (DFT) optimized structures at the B3LYP/6-311 G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state.

Crystal structure of high-spin tetra-aqua-bis-(2-chloro-pyrazine-κN (4))iron(II) bis-(4-methyl-benzene-sulfonate).

The title salt, [Fe(II)(C4H3ClN2)2(H2O)4](C7H7O3S)2, contains a complex cation with point group symmetry 2/m. The high-spin Fe(II) cation is hexa-coordinated by four symmetry-related water and two N-bound 2-chloro-pyrazine mol-ecules in a trans arrangement, forming a distorted FeN2O4 octa-hedron. The three-dimensional supra-molecular structure is supported by inter-molecular O-H⋯O hydrogen bonds between the complex cations and tosyl-ate anions, and additional π-π inter-actions between benzene and pyrazine rings. The methyl H atoms of the tosyl-ate anion are equally disordered over two positions.

Diaquabis-[3-(hydroxy-imino)-butanoato]nickel(II).

In the neutral, mononuclear title complex, [Ni(C(4)H(6)NO(3))(2)(H(2)O)(2)], the Ni atom lies on a crystallographic inversion centre within a distorted octa-hedral N(2)O(4) environment. Two trans-disposed anions of 3-hydroxy-imino-butanoic acid occupy four equatorial sites, coordinated by the deprotonated carboxyl-ate and protonated oxime groups and forming six-membered chelate rings, while the two axial positions are occupied by the water O atoms. The O atom of the oxime group forms an intra-molecular hydrogen bond with the coordinated carboxyl-ate O atom. The complex mol-ecules are linked into chains along b by hydrogen bonds between the water O atom and the carboxyl-ate O of a neighbouring mol-ecule. The chains are linked by further hydrogen bonds into a layer structure.

Diaquabis-[3-(hydroxy-imino-)butanoato]nickel(II): a triclinic polymorph.

The title centrosymmetric mononuclear complex, [Ni(C(4)H(6)NO(3))(2)(H(2)O)(2)], is a polymorph of the previously reported complex [Dudarenko et al. (2010 ▶). Acta Cryst. E66, m277-m278]. The Ni(II) atom, lying on an inversion center, is six-coordinated by two carboxyl-ate O atoms and two oxime N atoms from two trans-disposed chelating 3-hydroxy-imino-butanoate ligands and two axial water mol-ecules in a distorted octa-hedral geometry. The hydr-oxy group forms an intra-molecular hydrogen bond with the coordinated carboxyl-ate O atom. The complex mol-ecules are linked in stacks along [010] by a hydrogen bond between the water O atom and the carboxyl-ate O atom of a neighboring mol-ecule. The stacks are further linked by O-H⋯O hydrogen bonds into a layer parallel to (001).