A square-planar Ni(II) complex with an asymmetric coordination of a novel polynucleative 2,6-diacetylpyridine bis{[2-(hydroxyimino)propanoyl]hydrazone} ligand

The title compound, (2,6-diacetylpyridine bis{[2-(hydroxyimino)propanoyl]hydrazone}(2-))nickel(II) dimethyl sulfoxide solvate monohydrate, [Ni(C(15)H(17)N(7)O(4))] x C(2)H(6)OS x H(2)O, represents the first example of square-planar N(4) coordination via N atoms with four different functions, namely amide, azomethine, hydroxyimino and pyridine. The coordination polyhedron of the central Ni atom has a slightly distorted square-planar geometry. The 2,6-diacetylpyridine bis{[2-(hydroxyimino)propanoyl]hydrazone} ligand forms one six- and two five-membered chelate rings, and a pseudo-chelate ring through an intramolecular hydrogen bond with an amide group as donor and a deprotonated hydroxyimino group as acceptor, resulting in a pseudomacrocyclic arrangement.