Synthesis, spectral and structural characterization of dinuclear rhodium (II) complexes of the anticonvulsant drug valproate with theophylline and caffeine

Abstract

The dinuclear complex tetra(μ-valproato) dirhodium(II), Rh2(valp)4 (1), and its bis-adducts with theophylline, Rh2(valp)4(ThH)2 (4), or caffeine, Rh2(valp)4(Caf)2 (5), have been synthesized and characterized by elemental analysis, IR, UV-Vis, magnetic moment, 1H and 13C NMR spectroscopic techniques. Spectral data for the complexes are consistent with a dinuclear structure as found for rhodium (II) tetracarboxylate adducts. Theophylline and caffeine bases in complexes 4 and 5, respectively, are axially coordinated to rhodium (II) atoms through the sterically hindered N(9) site. This is confirmed by X-ray crystal structure analyses of complexes 4 and 5.