TERNARY COMPLEXES OF TRANS-PT(NH3)2CL2 WITH AMINO-ACIDS AND NUCLEOBASES

The reactions of trans-[(NH3)2Pt(nucl)X]Y [X = Cl-, H2O, Y = Cl-, NO3-, ClO4- and nucl = 1-methylcytosine (1-MeC)] and 9-methylguanine (9-MeG) with the amino acids glyH = glycine, alaH = L-alanine, 2-aba = 2-L-aminobutyric acid, valH = L-valine and nvalH = L-norvaline, in aqueous solutions, produced the ternary complexes trans-[(NH3)2Pt(1-MeC)(gly)](NO3) (1A), trans-[(NH3)2Pt(1-MeC)(ala)](NO3).2H2O (2A), trans-[(NH3)2Pt(1-MeC)(2-aba)](NO3) (3A), trans-[(NH3)2Pt(1-MeC)(nval)](NO3) (4A), trans-[(NH3)2Pt(1-MeC)(valH)](NO3)2 (5A), trans-[(NH3)2Pt(9-MeG)(gly)](NO3)2.H2O (1B), trans-[(NH3)2Pt(9-MeG)(alaH)](ClO4)2 (2B), trans-[(NH3)2Pt(9-MeG)(2-aba)] (NO3) (3B), trans-[(NH3)2Pt(9-MeG)(nval)](NO3) (4B) and trans-[NH3)2Pt(9-MeG)(val)] (NO3) (5B). These were characterized in the solid state with elemental analysis, conductivity measurements, IR and H-1 NMR spectra. Only complexes 1A, 2A, 5A, 1B and 2B were analytically pure, while the others contained small amounts of NaNO3, which, however, did not prevent their spectroscopic study. Both nucleobases 1-MeC and 9-MeG retain their N3 and N7 coordinations in the ternary systems. Very weak hydrophobic ligand-ligand interactions were observed in solution with H-1 NMR in the present system, weaker even than in the corresponding cis system.