Magnetic properties of copper(II) complexes containing peptides. Crystal structure of [Cu(phe-leu)]

A novel copper(II) complex containing the peptide phe-leu has been prepared and characterized. The crystal structure of [Cu(phe-leu)] (1) was determined by X-ray diffraction. The presence of carboxylate and amido bridges allows the formation of an extended 2D arrangement. This structure is similar to those found in [Cu(gly-val)] · 1/2H2O (2), [Cu(val-gly)] (3), [Cu(val-phe)] (4), and [Cu(phe-phe)] (5). The magnetic properties of compounds 1–5 were studied and analyzed comparatively. The experimental data show that the magnetic interactions are mainly transmitted through μ2-COO− bridges, being ferromagnetic for 1 and 3, and antiferromagnetic for 2, 4 and 5.