Binuclear cobalt(II/II) and cobalt(II/III) chelates with O2N2 ligands: synthesis, structure and magnetic studies

The title complexes [(Co2L21)-L-II] and [(CoCoIII)-Co-II-(OAc)L-2(2)] have been synthesized in excellent yields by reacting Co(OAc)(2)center dot 4H(2)O with H2L1 and H2L2, respectively, in acetonitrile solution. Here, [L-1](2-) and [L-2](2-) are the deprotonated forms of N,N-bis(2-hydroxybenzyl)-N',N'- dimethylethylenediamine and N,N-bis(2-hydroxybenzyl)-2- picolylamine, respectively. The crystal structures of [(Co2L21)-L-II] and [(CoCoIII)-Co-II(OAc)L-2(2)]center dot H2O center dot Ch(2)Cl(2) were determined by x-ray crystallography. In [(Co2L21)-L-II], each cobalt atom has distorted trigonal bipyramid geometry, while in [(CoCoIII)-Co-II(OAc)L-2(2)], each cobalt atom has distorted octahedral geometry. Variable temperature magnetic moment measurements show weak antiferromagnetic interaction in [(Co2L21)-L-II]. The magnetic characterization for [(CoCoIII)-Co-II(OAc)L-2(2)] is in agreement with the presence of Co(II) and Co(III) centers.