High-spin five-co-ordinate nickel(II) and cobalt(II) complexes with 2,6-diacetylpyridinebis(imines)

Abstract

The Schiff bases obtained from 2,6-diacetylpyridine and various aliphatic amines behave as tridentate ligands with set of donor atoms NNN in nickel(II) and cobalt(II) complexes. The complexes have the general formula MLX2(M = Ni or Co; L = 2,6-diacetylpyridinebisimine; and X = halogen or pseudohalogen) and are all of the high-spin type. The nickel and cobalt halide complexes are five-co-ordinate both in the solid state and in solution, while the nickel and cobalt nitrate complexes are octahedral. The cobalt thiocyanate complexes are monomeric and five-co-ordinate, while the nickel thiocyanate complexes achieve a polymeric octahedral structure, presumably through intermolecular bridging linkages of the thiocyanate groups.