Synthesis and magnetism of mu-2-bromoterephthalato copper(II) binuclear complexes

Three new copper(II) binuclear complexes namely, [Cu-2(BTPHA)(Phen)(2)(ClO4)(2)] (complex 1), [Cu-2(BTPHA)(Nphen)(2)(ClO4)(2)] (complex 2) and [Cu-2(BTPHA)(Bpy)(2) (ClO4)(2)] (complex 3) (BTPHA = 2-bromoterephthalate, Phen = 1,10-phenanthroline, Nphen = 5-nitro-1, 10-phenanthroline, Bpy = 2,2-bipyridil), have been synthesized with 2-bromoterephthalato as the bridged ligand. The complexes were characterized by elemental analysis, IR, ESR and electronic reflection spectra. The complexes have extended 2-bromoterephthalato-bridged structure and consist of two copper(II) ions. The variable-temperature magnetic susceptibilities of the complexes were measured over 77-300 K. The magnetic coupling parameters are consistent with antiferromagnetic exchange model based on the Hamiltonian operator [(H) over cap = -2J (S) over cap(perpendicular to)(S) over cap(2), S-1 = S-2 = 1/2], giving the antiferromagnetic coupling parameters of 2J = -9.2 cm(-1) for the three complexes.