Complexes of Di-2-pyridyl ketone. I. Complexes of first-row transition elements in normal oxidation states

Abstract

All the complexes of di-2-pyridyl ketone (DPK) described appear to involve N,N-chelation of the ligand. In CU(DPK)2SO4,2H2O the water molecules are added across the ketone groups yielding gem-dihydroxy functions. Several previously reported solvated DPK-cupric complexes which were assigned N,O-chelated structures probably have analogous N,N-chelated structures with solvent molecules (H2O or alcohols) added across the ketone group. The compounds M(DPK)2Cl2 (M = MnII, FeII, CoII, NiII) are tentatively assigned cis-octahedral structures, and a number of mono- and bis-DPK-cupric complexes appear to have the common tetragonal or square-planar geometries. The compounds of stoicheiometry Co(DPK)2(OH)2Cl,�H2O and CO(DPK)2(OH)2NO3, prepared from the corresponding cobalt(11) salts, are cobalt(111) derivatives in which one or both of the DPK units is reduced and probably acts as a tridentate ligand.