SYNTHESIS AND MAGNETIC PROPERTIES OF NEW TRINUCLEAR LANTHANIDE(III) COMPLEXES BRIDGED BY TEREPHTHALATO GROUPS

摘要

Eighteen lanthanide (III) complexes, presumably trinuclear, have been synthesized and characterized, namely [Ln(3)(TPHA)(3)(L)(3)](ClO4)(3) . 3H(2)O (L = 2,2'-bipyridyl (bpy), 1,10-phenanthroline (phen), 4,4'-dimethyl-2,2'-bipyridyl (Me(2)bpy) 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 [Gd-3(TPHA)(3)(NO2-phen)(3)](ClO4)(3) . 3H(2)O were measured over the 4-300 K range and the observed data were successfully simulated by an equation based on the spin Hamiltonian operator ((H) over cap = -2J((S) over cap(1) . + (S) over cap(2) + (S) over cap(1) . (S) over cap(3) + (S) over cap(2) . <(S)over cap(3))). 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. [References: 26]