Structure and stability of carboxylate complexes. Part V. Crystal and molecular structures of bis(methoxyacetato)bis(pyridine)copper(II) tetrahydrate and bis(phenoxyacetato)aquobis(pyridine)copper(II)

Abstract

The crystal structures of bis(methoxyacetato)bis(pyridine)copper(II) tetrahydrate (triclinic, a= 8·55, b= 9·25, c= 7·50 Å, α= 97·5, β= 70·1, γ= 86·4°, P) and bis(phenoxyacetato)aquobis(pyridine)copper(II)(orthorhombic, a= 11·29, b= 37·74, c= 5·87 Å, P2₁2₁2₁) have been determined by three-dimensional X-ray analysis. In the former, the copper(II) atom is at a centre of symmetry, with trans pairs of pyridine and chelating methoxyacetate ligands. The copper co-ordination octahedron is elongated in the direction of the Cu–OMe bonds (2·36 Å) which are themselves longer than in the bis(methoxyacetato)diaquocopper(II) complex (2·13 Å). In the second title-named complex, the copper(II) atom is in a five-co-ordinate square-pyramidal environment with the aquo-ligand at the apex and trans pairs of pyridine and unidentate phenoxyacetato-ligands in the basal plane. In the refinements by the least-squares method, convergence was reached at R= 0·10 for the former and R= 0·089 for the latter.