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 L1Cu (L1H2 standing for 1,3-bis((3-methoxysalicylidene)amino)-2,2‘-dimethylpropane) reacts with GdCl3·6H2O to afford a dinuclear complex which crystallizes in the orthorhombic space group Pca21 (No. 29) in a cell having the dimensions a = 9.0246(11) Å, b = 16.5198(14) Å, c = 20.286(2) Å, and Z = 4. Analysis of the structural data shows that it may be formulated as [L1CuCl2Gd(H2O)4]Cl·2H2O. 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 L1CuGdX3·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.