Abstract
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.
Highlights
C—HÁ Á ÁCl interactions, leading to a three-dimensional network structure
The tetranuclear complex in another dichlorido-bridged copper (II) lies about a crystallographic inversion centre and has one core in which two CuII metal centers are mutually interconnected 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 3-mode
Summary
The condensation reaction of pyridine-2-carbaldehyde and nicotinic acid hydrazide in ethanol in the presence of copper acetate yields two different complexes whose ligands are respectively a hemiacetal [ethoxy(pyridine-2-yl)methanol] and a condensation product [({1-[1-ethoxy-1-(pyridin-2-yl)methylene]}-2-(oxonicotinyl))hydrazine]. In the CuO2NCl2 units, the Cu2 (Cu2i) atoms are linked to one 2-O and one 3-O atoms from a deprotonated hydroxyl groups and one chloride ion to two other CuII cations with Cu1—Cu2 and Cu1—Cu2i distances of approximately 3.012 and 3.408 A , respectively. These are in good agreement with literature values (Qin et al, 2014). An immediate consequence is a small Cu1Á Á ÁCu2 separation [3.4082 (4) A ] compared to those found in another dichlorido-bridged copper (II) complex (Banerjee et al, 2013)
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