A novel binuclear copper(II) complex with fumarate and 1,10-phenanthroline

A MeOH solution of 1,10-phenanthroline reacts with Cu(fum)[fum = (OOCCH = CHCOO)^2–] to yield a novel binuclear copper(II) unsaturated dicarboxylate complex of general formula [Cu₂(fum)(phen)₄](fum) · 11H₂O, whose crystal structure has been determined by X-ray diffraction. Two copper(II) atoms are bridged by a fumarate group, and each copper(II) atom is coordinated to two 1,10-phenanthroline molecules in a distorted trigonal bipyramidal configuration. The i.r. spectrum shows the presence of the monodentate carboxylate ligand. The electronic reflectance spectrum in the solid state suggest that the d–d transitions of the complex is in a trigonal bipyramidal ligand field. The temperature-dependent magnetic susceptibility studies suggest that a weak ferromagnetic interaction exists between the two copper(II) atoms when the temperature exceeds 130 K.