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

Abstract

Novel binuclear Co(II) complexeswithN-functionalized cyclam N,N?,N",N???-tetrakis( 2-pyridylmethyl)tetraazacyclotetradecane (tpmc) and one of the aromatic monoor 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 andmagnetic as well as cyclic voltammetric measurements. In [Co2(C6H5COO)2tpmc]ClO4)2.3H2O, the benzoate ligands are most probably coordinated 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-phthalate dianizon, z = 2; 4) it is proposed that the isomeric dicarboxylates are bonded combined as bridges and chelates. The composition and the assumed geometries of the complexes are compared with the, earlier reported, corresponding Cu(II) complexes. Cyclic voltammetry measurements showed that the compounds are electrochemically stable.