Synthesis and magnetic properties of mu-chloranilato iron(III) binuclear complexes

摘要

Six new iron(III) binuclear complexes have been synthesized and characterized, namely [Fe-2(CA)L-4] (ClO4)(4) [L denotes 2,2'-bipyridine (bpy); 1,10-phenanthroline (phen); 4,4'-dimethyl-2,2'-bipyridine (Me(2)bpy); 5-methyl-1,10-phenanthroline (Me-phen); 5-chloro-1,10-phenanthroline (Cl-phen) and 5-nitro-1,10-phenanthroline (NO2-phen)], where CA represents the dianion;of chloranilic acid. Based on elemental analyses, molar conductivity and magnetic moment measurements, and spectroscopic studies, it is proposed that these complexes have CA-bridged structures and consist of two iron(III) ions in a distorted octahedral environment. The complexes [Fe-2(CA)(bpy)(4)](ClO4)(4) (1) and [Fe-2(CA)(phen)(4)] (ClO4)(4) (2) were characterized by variable temperature magnetic susceptibility measurements (4-300 K) and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, (H) over cap = -2J (S) over cap(1) .(S) over cap(2), giving the exchange integral J = -2.1 cm(-1) for (1) and J = -5.8 cm(-1) for (2). This result indicates that there is a weak antiferromagnetic spin-exchange interaction between two of the Fe(III) ions within each molecule. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 20]