Interactions of tetrakis(-µ-carboxylato)dirhodium( II ), an antitumour agent, with nucleic acid bases. X-Ray crystal structures of [Rh 2 (acetato) 4 (theophylline) 2 ] and [Rh 2 (acetato) 4 (caffeine) 2 ]

X-Ray crystal structure analyses of tetrakis(-µ-acetato)dirhodium(II) complexes of theophylline and caffeine have shown that in both complexes the dirhodium–tetra-acetate nucleus is occupied at the two axial positions by N(9) of the theophylline and caffeine bases.