Crystal structure of bis-{µ-2-meth-oxy-6-[(methyl-imino)-meth-yl]phenolato}bis-({2-meth-oxy-6-[(methyl-imino)-meth-yl]phenolato}nickel(II)) involving different coordination modes of the same Schiff base ligand.

The structure of the title compound, [Ni2(C9H10NO2)4], is built up by discrete centrosymmetric dimers. Two nitro-gen and three oxygen atoms of two Schiff base ligands singly deprotonated at the phenolate site form a square-pyramidal environment for each metal atom. The ligands are bonded differently to the metal centre: one of the phenolic O atoms is bound to one nickel atom, whereas another bridges the two metal atoms to form the dimer. The Ni-N/O distances fall in the range 1.8965 (13)-1.9926 (15) Å, with the Ni-N bonds being slightly longer; the fifth contact of the metal to the bridging phenolate oxygen atom is substanti-ally elongated [2.533 (1) Å]. A similar coordination geometry was observed in the isomorphous Cu analogue previously reported by us [Sydoruk et al. (2013 ▸). Acta Cryst. E69, m551-m552]. In the crystal, the [Ni2 L 4] mol-ecules form sheets parallel to the ab plane with the polar meth-oxy groups protruding into the inter-sheet space and keeping the sheets apart. Within a sheet, the mol-ecules are stacked relative to each other in such a way that the Ni2O2 planes of neighbouring mol-ecules are orthogonal.