Reactivity of coordinated nitriles - Formation of the acetamidine complex cis-[(PMe3)(2)Pt{1-MeTy(-H)}{CH3C(NH)NH2}](+) from the 1-methylthyminate compound cis-[(PMe3)(2)Pt{1-MeTy(-H)}(CH3CN)](+) - Synthesis, characterisation, and X-ray structures

1-Methylthymine (1-MeTy) reacts reversibly with the hydroxo complexes cis-[ (PMe3)(2)Pt(mu -OH)](2)X-2 (X- = NO3; ClO4) in various solvents (S = CH3CN, H2O, DMSO) to give the thyminate derivatives cis-[(PMe3)(2)Pt{1-MeTy(-H)}( S)]X that have been isolated as pure compounds when S is CH3CN. The single- crystal X-ray structure of cis-[(PMe3)(2)Pt{1-MeTy(-H)}(CH3CN)]ClO4 shows t hat the N(3)-platinated nucleobase acts as a monodentate ligand and a molec ule of CH3CN completes the coordination sphere of the metal. Crystals of th e acetamidine derivative cis-[(PMe3)(2)Pt{1-MeTy(-H)}{CH3C(NH)NH2}]X were i solated from an acetonitrile solution of this complex, in the presence of s mall amounts of water, after several months at room temperature, separated in 5-10% yield. The X-ray analysis of the perchlorate salt shows a configur ation of the amidine ligand consistent with a formal trans addition of NH3 to the CN triple bond of the coordinated nitrile. The acetamidine complex w as formed in high yield (70%), in a few weeks, when aqueous solution of NH3 was added to cis-[(PMe3)(2)Pt{1-MeTy(-H)}(CH3CN)](+) dissolved in CH3CN. S ide products of this reaction are the ammonia complex cis-[(PMe3)(2)Pt{1-Me Ty(-H)}(NH3)](+), which was also obtained as pure compound, acetamide, and other platinum containing species. All the isolated complexes were characte rised by elemental analysis, IR, and multinuclear NMR spectroscopy.