Crystal and molecular structure and magnetic properties of a trinuclear complex containing exchange-coupled GdCu2 species

Abstract

gadolinium(II1) and europium(II1) nitrate to yield a compound of formula (CUSAL~~)~M(H,O)(NO~)~(.M~ =E ~euNroOp,ium(\nIII), gadolinium(II1)). The crystal structure of the gadolinium complex was determined at room temperature: the compound\ncrystallizes in the triclinic space group Pi, with a = 15.694 (2) A; b = 14.887 (1) A, c = 10.574 (2) A, a = 95.44 (O)O, p = 103.18\n( 5 ) O , y = 106.95 (O)’, and Z = 2. Least-squares refinement of the structure led to a conventional R factor of 0.041. The\neuropium(I11) ion derivative was found to be isomorphous. The gadolinium(II1) ion is nine-coordinated by the oxygen atoms of\ntwo CuSALtn moieties, two bidentate nitrate ions, and one water molecule. The coordination geometry can be described as a\ntricapped trigonal prism. The effective magnetic moment of the compound was found to increase on decreasing the temperature.\nThe experimental points were fit to a spin-Hamiltonian model for symmetric triples of spins, to yield a weak ferromagnetic\ngadolinium(II1)-copper(1I) interaction and a weak antiferromagnetic copper(I1)-copper(I1) interaction. The coupling between\nthe two copper ions was confirmed by the triplet EPR spectra of the europium(II1) derivative.