Influence of anionic ligands (X) on the nature and magnetic properties of dinuclear LCuGdX3•nH2O complexes (LH2 standing for tetradentate Schiff base ligands deriving from 2-hydroxy-3-methoxybenzaldehyde and X being Cl, N3C2, and CF3COO)

The monometallic precursor (LCu)-Cu-1 ((LH2)-H-1 standing for 1,3-bis((3-methoxysalicylidene)amino)-2,2'-dimethylpropane) reacts with GdCl3.6H(2)O to afford a dinuclear complex which crystallizes in the orthorhombic space group Pca2(1) (No. 29) in a cell having the dimensions a = 9.0246(11) Angstrom, b = 16.5198(14) Angstrom, c = 20.286(2) Angstrom, and Z = 4. Analysis of the structural data shows that it may be formulated as [(LCuCl2Gd)-Cu-1(H2O)(4)]Cl.2H(2)O. The cationic dinuclear unit possesses a CuO2Gd bridging core which is almost planar. The complex displays a ferromagnetic interaction (10.1 cm(-1)) which is the largest yet reported for a structurally characterized dinuclear (Cu-Gd) complex. Lower magnetic interactions are observed for neutral (LCuGdX3)-Cu-1.H2O complexes (X = N3C2, CF3COO). Consideration of the magnetic and structural data obtained for various dinuclear (Cu-Gd) complexes leads to a correlation between the magnitude of the magnetic interaction and the exponential of the dihedral angle between the two halves of the CuO2Gd bridging core.