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

The dinuclear complex tetra(mu-valproato) dirhodium(II), Rh-2(valp)(4) (1), and its bis-adducts with theophylline, Rh-2(valp)(4)(ThH)(2) (4), or caffeine, Rh-2(valp)(4)(Caf)(2) (5), have been synthesized and characterized by elemental analysis, IR, UV-Vis, magnetic moment, H-1 and C-13 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. (C) 2009 Elsevier B. V. All rights reserved.