Multinuclear magnetic resonance studies of the reactions of the antitumor complexes cis-Pt(L)(2)X-2 and cis-Pt(NH3)(L)X-2 (L = cyclobutylamine and cyclopentylamine) with guanosine and other bases and crystal structures of Pt(cyclopentylamine)(2)I-2

摘要

The crystal structures of two Pt(cyclopentylamine) I-2(2) compounds were determined by X-ray diffraction methods. Both crystals contain disordered cyclopentylamine ligands. Crystal I contains two independent trans-Pt(cyclopentylamine)(2)I-2 molecules and all the C atoms are disordered on two positions. The second crystal (II) is most interesting since it contains both cis- and trans-Pt(cyclopentylamine)(2)I-2 isomers in the same unit cell. It was prepared from the recrystallization of the cis isomer in acetone. The C atoms of the trans molecule in crystal II are disordered on two positions, while only one position was determined in the cis molecule, although some of the C thermal factors are quite high. The reactions of cis-Pt(amine)(2)X-2 and cis-Pt(NH3)(amine) X-2 (amine = cyclobutylamine and cyclopentylamine) with guanosine in water were studied in different Pt: guanosine proportions by multinuclear (H-1, Pt-195 and N-15) magnetic resonance spectroscopy. The presence of several species in solution was observed. For the mixed-cyclobutylamine compound, N-15 NMR has shown that some of the NH3 ligands have been displaced from the coordination sphere in the presence of an excess of guanosine. The reactions of the two mixed-ligand complexes cis-Pt(NH3)(amine) Cl-2 with 9-methylguanine, inosine and 9-methylhypoxanthine were also studied in water and the results are discussed.