Effect of remote substituents and coordination anions on the magnetic properties of Co(ii) dimer complexes

Four Co(II) complexes [Co-2(II)(H(2)L1)Cl-2]center dot 2MeCN (1), [Co-2(II)(H(2)L2)Cl-2] (2), [Co-2(II)(H(2)L1)(acac)(2)]center dot 2MeCN (3), and [Co-2(II)(H(2)L2)(acac)(2)](2) (4) (acac = acetylacetone, H(2)L1 = N,N'-bis[(2-hydroxybenzylideneamino)propyl] piperazine, H(2)L2 = N,N'-bis(2-hydroxy-5-bromobenzyl)-1,4-bis(3-iminopropyl)piperazine) based on symmetric Schiff base ligands were synthesized and charactered. They are all symmetric Co(II) dimers, in which Co(II) ions in complexes 1 and 2 are four-coordinate tetrahedral, and Co(II) ions in complexes 3 and 4 are five-coordinate trigonal bipyramidal. The coordination geometries of the Co(II) ions change from tetrahedral to trigonal bipyramidal by regulating the coordination anions. Furthermore, remote substituents of the aromatic benzene rings in the ligands were fine-tuned. Magnetic studies indicate that remote substituents of the ligands, as well as the coordination geometries, have no significant effect on the magnetic properties of these four Co(II) dimer complexes.