Syntheses, crystal structures, and properties of Ni(II) and Co(III) complexes derived from tripod polypyridine ligands containing N7 or N6 donor set atoms

The reaction of Ni2+ and Co2+ ions with tripod heptadentate pbpaen ligand in ethanol gives octahedral [NiII(pbpaen)](ClO4)2 and [CoIII(pbpaen)](ClO4)3 complexes. In acidic medium (pH ≈ 4), only the Co2+ ion gives an octahedral [CoIII(bpaen)](ClO4)3 compound in which one pyridylmethyl group of tripod pbpaen ligand has been eliminated giving new bpaen ligand.