Substitution process in phosphine thiopurine palladium complexes

The synthesis and characterization of the new palladium phosphane thiopurine complexes [PdCl(Py)(PPh3)(8-MTT)] (1) (8-MTTH=8-methylthiotheophylline) and [PdBr(Py)(PPh3)(8-BzTT)] (2) (8-BzTTH=8-benzylthiotheophylline) are presented. Both complexes have been studied by IR and multinuclear (1H, 31P{1H}) NMR spectroscopy. In addition, the solid state structure of 2 has been authenticated by X-ray crystallography. In this complex, a square-planar coordination around palladium occurs through a deprotonated N7 8-BzTT− atom trans to a Br− atom, and cis to a PPh3 and to a pyridine. The substitution process that exchanges one of the two PPh3 ligands in trans-[PdCl(PPh3)2(8-MTT)] by a pyridine to produce 1 has also been studied by multinuclear NMR and GS–MS.