Structure and stability of carboxylate complexes. Part III. Crystal and molecular structure of diaquobis(methoxyacetato)nickel(II) and crystal data for tetra-aquobis(phenoxyacetato)nickel(II)

Abstract

The crystal and molecular structure of diaquobis(methoxyacetato)nickel(II) has been determined by three-dimensional X-ray methods (R= 0·119). The monoclinic unit cell, space group P2₁/n, has dimensions a= 6·90 ± 0·02, b= 7·15 ± 0·02, c= 10·05 ± 0·03 Å, γ= 99·8 ± 0·3°, with Z= 2. The complex is a chelate and isostructural with its copper analogue. The carboxylate ligand dimensions and angles are equal within experimental error and the hydrogen-bond system is equivalent but in the nickel co-ordination octahedron the observed bond lengths are Ni–OMe 1·99, Ni–OH₂ 2·07, and Ni–OCO 2·05 Å. The longer Cu–OMe (2·13 Å) contact in the copper complex appears to be due neither to steric hindrance nor to low bonding ability of the ethereal oxygen atom. In tetra-aquobis(phenoxyacetato)nickel(II), the carboxylate ligands are unidentate.