Crystal structures of two nickel compounds comprising neutral NiII hydrazone complexes and di-carb-oxy-lic acids

Crystal structure and Hirshfeld surface analysis of 2,5-di-bromo-terephthalic acid ethyl-ene glycol monosolvate

The title compound, C8H4Br2O4·C2H6O2, crystallizes with one-half of a 2,5-di-bromo-terephthalic acid (H2Br2tp) mol-ecule and one-half of an ethyl-ene glycol (EG) mol-ecule in the the asymmetric unit. The whole mol-ecules are generated by application of inversion symmetry. The H2Br2tp mol-ecule is not planar, with the di-bromo-benzene ring system inclined by a dihedral angle of 18.62 (3)° to the carb-oxy-lic group. In the crystal, the H2Br2tp and EG mol-ecules are linked into sheets propagating parallel to (01) through O-H⋯O hydrogen bonds, thereby forming R 4 4 (12) and R 4 4 (28) graph-set motifs. Br⋯O and weak π-π stacking inter-actions are also observed. Hirshfeld surface analysis was used to confirm the existence of these inter-actions.

Crystal structures of two CuII compounds: catena-poly[[chlorido-copper(II)]-μ-N-[eth-oxy(pyridin-2-yl)methyl-idene]-N'-[oxido(pyridin-3-yl)methyl-idene]hydrazine-κ4 N,N',O:N''] and di-μ-chlorido-1:4κ2 Cl:Cl-2:3κ2 Cl:Cl-di-chlorido-2κCl,4κCl-bis[μ3-eth-oxy(pyridin-2-yl)methano-lato-1:2:3κ3 O:N,O:O;1:3:4κ3 O:O:N,O]bis-[μ2-eth-oxy(pyridin-2-yl)methano-lato-1:2κ3 N,O:O;3:4κ3 N,O:O]tetracopper(II)

Two CuII complexes [Cu(C14H13N4O2)Cl] n , I, and [Cu4(C8H10NO2)4Cl4] n , II, have been synthesized. In the structure of the mononuclear complex I, each ligand is coordinated to two metal centers. The basal plane around the CuII cation is formed by one chloride anion, one oxygen atom, one imino and one pyridine nitro-gen atom. The apical position of the distorted square-pyramidal geometry is occupied by a pyridine nitro-gen atom from a neighbouring unit, leading to infinite one-dimensional polymeric chains along the b-axis direction. Each chain is connected to adjacent chains by inter-molecular C-H⋯O and C-H⋯Cl inter-actions, leading to a three-dimensional network structure. The tetra-nuclear complex II lies about a crystallographic inversion centre and has one core in which two CuII metal centers are mutually inter-connected via two enolato oxygen atoms while the other two CuII cations are linked by a chloride anion and an enolato oxygen. An open-cube structure is generated in which the two open-cube units, with seven vertices each, share a side composed of two CuII ions bridged by two enolato oxygen atoms acting in a μ3-mode. The CuII atoms in each of the two CuO3NCl units are connected by one μ2-O and two μ3-O atoms from deprotonated hydroxyl groups and one chloride anion to the three other CuII centres. Each of the penta-coordinated CuII cations has a distorted NO3Cl square-pyramidal environment. The CuII atoms in each of the two CuO2NCl2 units are connected by μ2-O and μ3-O atoms from deprotonated alcohol hy-droxy groups and one chloride anion to two other CuII ions. Each of the penta-coordinated CuII cations has a distorted NO2Cl2 square-pyramidal environment. In the crystal, a series of intra-molecular C-H⋯O and C-H⋯Cl hydrogen bonds are observed in each tetra-nuclear monomeric unit, which is connected to four tetra-nuclear monomeric units by inter-molecular C-H⋯O hydrogen bonds, thus forming a planar two-dimensional structure in the (01) plane.