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

The structure of the title compound, [Ni-2(C9H10NO2)(4)], is built up by discrete centrosymmetric dimers. Two nitrogen 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) angstrom, with the Ni-N bonds being slightly longer; the fifth contact of the metal to the bridging phenolate oxygen atom is substantially elongated [2.533 (1) angstrom]. 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 [Ni2L4] molecules form sheets parallel to the ab plane with the polar methoxy groups protruding into the intersheet space and keeping the sheets apart. Within a sheet, the molecules are stacked relative to each other in such a way that the Ni2O2 planes of neighbouring molecules are orthogonal.