Mononuclear and polynuclear complexes of cobalt(II) carboxylates with pyridine and other heterocyclic bases

Adducts of cobalt(II) carboxylates with pyridine and related ligands have been prepared, their electronic spectra assigned, and their magnetic properties investigated. The complex [Co(py)2(O2CPh)2](py = pyridine) behaves as a six-co-ordinate species whose electronic spectrum shows retragonal splitting; [Co(2-Mepy)(O2CPh)2] has the properties of a trigonal-bipyramidal five-co-ordinate high-spin complex. The green complexes [Co2(quin)2-(O2CR)4](R = Ph or C6H4NO2-2; quin = quinoline) are antiferromagnetic binuclear species with square-pyramidal five-co-ordination. A slate-blue form of [Co(quin)(O2CC6H4NO2-2)2] behaves as a slightly antiferro-magnetic polymer. The complexes [Co3(quin)2(O2CR)6](R = Ph or C6H4NO2-2) contain a linear array of two trigonal-bipyramidal and one octahedral cobalt atoms and are not appreciably antiferromagnetic.