Pt(II) compounds with sulfoxide ligands and crystal structures of complexes of the types I(R2SO)Pt(μ-I)2Pt(R2SO)I and trans-Pt(R2SO)(L)X2 (L = amine,pyridine and pyrimidine)

The crystal structures of several Pt(II) complexes containing sulfoxide ligands are described. The two iodo bridged dimers of the type I(R₂SO)Pt(μ-I)₂Pt(R₂SO)I (where R is ethyl or n-butyl) are twinned structures. The dinuclear species are the trans isomers. Two compounds of the type trans-Pt(DMSO)(amine)X₂ were studied by X-ray diffraction methods. The diiodo MeNH₂ compound forms H-bonded chains, formed by maximizing the H-bonds between the amine group with the O atom of DMSO and one iodo ligand. The H-bonding pattern is quite different in the dichloro t-BuNH₂ complex. In the latter crystal, there are two independent molecules which are H-bonded in pairs. The methyl groups of DMSO and the t-butyl group of the amine are oriented towards the outside of the pairs of molecules, while the H-bonds link the two independent molecules. Again, the amino group forms the maximum H-bonds with the O atom of DMSO and one chloro ligand. The crystal structures of trans-Pt(DMSO)(pyridine)I₂ and of trans-Pt(MeBzSO)(pyrimidine)I₂ (Bz = benzyl) were also studied. In the pyridine complex, the O atom of DMSO is in the Pt(II) plane by symmetry, while in the pyrimidine compound, the C atom of the –CH₃ group is in the Pt(II) plane. The pyridine and the pyrimidine ligands are perpendicular to the Pt(II) square plane. The trans influence of the different ligands is discussed.