Synthesis and magnetic properties of chloroanilato-bridged manganese(II) binuclear complexes

Abstract

Five chloroanilato-bridged manganese(II) binuclear complexes, [Mn2(CA)L4](ClO4)2, where L = 4,4′-dimethyl-2,2′-bipyridine (Me2-bpy), 5-methyl-1,10-phenanthroline (Me-phen), 5-chloro-1,10-phenanthroline (Cl-phen), 5-nitro-1,10-phenanthroline (NO2-phen) and 2,9-dimethyl-1,10-phenanthroline (Me2-phen), and CA represents the dianion of chloroanilic acid, have been synthesized and characterized by elemental analyses, molar conductivity and room temperature magnetic moment measurements, and by spectroscopy. It is proposed that these complexes have CA-bridged structures and consist of two manganese(II) ions in a distorted-octahedral environment. The complexes [Mn2(CA)(Me2-bpy)4](ClO4)2 (1) and [Mn2(CA)(Me-phen)4](ClO4)2 (2) were characterized by variable temperature magnetic susceptibility measurements (4–300 K) and the observed data were successfully simulated by an equation based on the spin Hamiltonian operator, Ĥ = −2JŜ 1 Ŝ 2, giving the exchange integral J = −1.98 cm−1 for (1) and J = −2.41 cm−1 for (2). This result indicates that there is a weak antiferromagnetic spin-exchange interaction between the two MnII ions within each molecule.