Bis[2-(hydroxyiminomethyl)phenolato]nickel(II): a second monoclinic polymorph

Abstract

The title compound, [Ni(C7H6NO2)2], (I), is a second monoclinic polymorph of the compound, (II), reported by Srivastava et al. [Acta Cryst. (1967), 22, 922] and Mereiter [Private communication (2002) CCDC refcode NISALO01]. The bond lengths and angles are similar in both structures. The molecule in both structures lies on a crystallographic inversion center and both have an internal hydrogen bond. The title compound crystallizes in the space group P21/c (Z = 2), whereas compound (II) is in the space group P21/n (Z = 2) with a similar cell volume but different cell parameters. In both polymorphs, molecules are arranged in the layers but in contrast to the previously published compound (II) where the dihedral angle between the layers is 86.3°, in the title polymorph the same dihedral angle is 29.4°. The structure of (I) is stabilized by strong intramolecular O—H...O hydrogen bonding between the O—H group and the phenolate O atom.