Macrocyclic and open-chain CuII-4f (4f=GdIII, CeIII) complexes with planar diamino chains:: Structures and magnetic properties

Until now, the known structures of heterodinuclear Cu-Ln complexes involve compartmental Schiff-base ligands with saturated diamino chains. We report here two Cu-Ln complexes (Ln = Gd or Ce) which are the first structurally characterized Cu-Ln entities involving S-methylisothiosemicarbazide as the diamino bridge, with open chain and macrocyclic ligands. The macrocyclic Cu-Gd entity is a well isolated dinuclear complex whereas two hydrogen bonds join together a pair of binuclear Cu-Ce complexes to give tetra nuclear {Cu-Ce...Ce-Cu} entities. The Cu-Gd complexes [H = -J(SCuSGd)] exhibit ferromagnetic interactions between 5 and 5.5 cm(-1). Since the Cu-Ce complexes do not follow the Curie law due to the presence of orbital degeneracy, an analysis based on a simple spin-only Hamiltonian is not possible. Nevertheless, the EPR spectra of the Cu-Ce complexes do confirm the existence of magnetic interactions. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).