Platinum complexes with pyridyl derivatives of 1,2,4-triazole

The chemistry of platinum(II) and platinum(IV) with the ligands 3,4,5-tris(2-pyridyl)-4-H-1,2,4-triazole, L1, and 3,5-di(2pyridyl)-4-(4-pyridyl)-4-H-1,2,4-triazole, L2, is described. The ligand L1 forms platinum(II) complexes [PtXY(kappa 2-N, N'-L1)] (X, Y = Cl, Cl; Cl, Me; Me, Me) by chelation while ligand L2 forms either analogous chelate complexes [PtXY(kappa 2-N, N'-L2)] (X, Y = Cl, Me; Me, Me) or acts as a monodentate ligand in forming trans-[PtCl2(SMe2)(kappa 1-N-L2)], in which only the 4-pyridyl group is coordinated. The electron-rich dimethylplatinum(II) complexes undergo oxidative addition reactions with methyl iodide to give [PtIMe3(kappa 2-N, N'-L1)], or with dichloromethane to give [PtClMe2(CH2Cl)(kappa 2-N, N'-L1)] or [PtClMe2(CH2Cl)(kappa 2-N, N'-L2)], each of which is formed as a mixture of three isomers. Structure determinations of several of these complexes are reported.