Cobalt(II) complexes with aromatic carboxylates and N-functionalized cyclam bearing 2-pyridylmethyl pendant arms

Novel binuclear Co(II) complexes with N-functionalized cyclam, N,N',N",N''' -te- trakis(2-pyridylmethyl)tetraazacyclotetradecane (tpmc) and one of the aromatic mono- or dicarboxylato ligands (benzoate, phthalate or isophthalate ions) were prepared. They were analyzed and studied by elemental analyses (C, H, N), electrical conductivities, VIS and IR spectroscopy and magnetic as well as cyclic voltammetric measurements. In Co2(C6H5COO)2tpmc(ClO4)2 . 3H2O, the benzoate ligands are most probably coordi- nated as chelates in the trans-position to each Co(II) and the macrocycle adopts a chair conformation. In the complexes Co2(Y)tpmc(ClO4)2 . zH2O, (Y = phthalate or i-phtha- late dianizon, z = 2; 4), it is proposed that the isomeric dicarboxylates are bonded com- bined as bridges and chelates. The composition and the assumed geometries of the com- plexes are compared with the, earlier reported, corresponding Cu(II) complexes. Cyclic voltammetry measurements showed that the compounds are electrochemically stable.