SYNTHESIS AND MAGNETISM OF TETRACHLOROPHTHALATO-BRIDGED COBALT(II) BINUCLEAR COMPLEXES

Three new cobalt(II) binuclear complexes have been prepared and charac terized, namely [Co-2(TCPHTA)(L)(4)](ClO4)(2) [L = 1,10-phenanthroline (phen), 5-ni tro-1,10-phenanthroline(NO2-phen) and 2, 2'-bipyridyl (b ipy), respectively], where TCPHTA is the tetrachlorophthalate dianion. Based on i.r. spectra, elemental analyses and conductivity measuremen ts, tetrachlorophthalato-bridged structures consisting of two cobalt(I I) ions in which each cobalt(II) ion has a distorted octahedral enviro nment are proposed for these complexes. The temperature dependence of the magnetic susceptibility for [Co-2(TCPHTA)(L)(4)](ClO4)(2) . nH(2)O (L = phen, NO2-phen and bipy) has been measured over the 77-300 K ran ge and the observed data successfully simulated by an equation based o n the spin Hamiltonian operator (H = -2JS(1)S(2)), giving the exchange integral J = -2.92, -3.45, -4.03 cm(-1), respectively. This result in dicates the presence of a weak antiferromagnetic spin exchange interac tion between the metal ions.