Homo- and heterodinuclear 2,2′-bipyrimidine-bridged complexes

[M'(hfacac)(2)(bpym)] complexes, where M' = Co-II, Ni-II or Zn-II, hfacac = hexafluoroacetylacetonate and bpym = 2,2'bipyrimidine; and [Cl2M(mu bpym)M'(hfacac)(2)] complexes, where M = Co-II, Ni-II Mn-II or Zn-II M' = Ni-II; M = Ni-II or Zn-II and M' = Zn-II; M = Ni-II and M' = Co-II have been prepared and characterized by chemical analysis, conductance measurements, IR and electronic spectroscopies and magnetic susceptibility measurements (4.2-292 K range). The dinuclear Ni-II-Ni-II, Co-II-Ni-II and Mn-II-Ni-II complexes are antiferromagnetic, with an intramolecular exchange parameter, J, of -2.3-8.9 cm(-1). Co-II and Mn-II are in a high spin state. The low temperature effect observed in monomers and in Ni-II-Zn-II dimers is considered a consequence of either an intermolecular antiferromagnetic interaction or the zero-field splitting in Ni-II.