Synthesis and Magnetic Properties of New Trinuclear Lanthanide (III) Complexes Bridged by Terephthalato Groups

Abstract

Abstract Eighteen lanthanide (III) complexes, presumably trinuclear, have been synthesized and characterized, namely [Ln3(TPHA)3(L)3](ClO4)3 · 3H2O (L = 2, 2′-bipyridyl (bpy), 1, 10-phenanthroline (phen), 4, 4′-dimethyl-2, 2′-bipyridyl (Me2bpy) and 5-nitro-1, 10-phenanthroline (NO2-phen)), where TPHA is the terephthalato dianion; Ln denotes Eu, Gd, Dy, Ho, Er, Nd. The variable temperature magnetic susceptibilities of [Gd3 (TPHA)3 (NO2-phen)3](ClO4)3 · 3H2O were measured over the 4—300 K range and the observed data were successfully simulated by an equation based on the spin Hamiltonian operator (Ĥ =—2J (Ŝ1 · Ŝ2 + Ŝ1 · Ŝ3 + Ŝ2 · Ŝ3)). The exchange integral J(Gd—Gd) was found to be—0.14 cm−1, indicating that a very weakly antiferromagnetic spin-exchange interaction operates between the adjacent gadolinium (III) ions in a trinuclear-triangular skeleton.