Review Article of American Journal of Chemical Research
THIO-LIGANDS in MONOMERIC Pt(II) COMPLEXES – STRUCTURAL ASPECTS
Milan Melník1, Peter Mikuš1 and Clive E. Holloway2
1Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic, 2York University, 4700 Keele st., North York M 3J 1P3, Ontario, Canada.
This review includes over three hundred derivatives in which each Pt(II) atom is in a distorted square planar environment with inner coordination spheres of PtS4, PtS3X, PtS2X2, PtSX3, PtS2XY, PtSX2Y and PtSXYZ. There is a wide variety of mono-, bi- , ter- , and tetra-dentate ligands, all incorporating both homo- and hetero-dentate varieties. The most common ligands are dimethylsulphoxide and triphenylphosphine. The chelating ligands create a wide variety of metallocyclic rings, where the effects of both steric and electronic factors are observed. Examples of cis– and trans– isomerism exists in these derivatives as well as distortion isomerism, which is much more common. Ligands exerting the trans– effect in these Pt(II) complexes are stronger in the order: OL, NL < Cl < Br < I < SL < H ~ AsL ~ PL ~ CN. Several relationships between the structural parameters were found and are discussed. The complexes crystallized in five crystal classes: hexagonal (0.4%) < tetragonal (1.5%) < orthorhombic (13.8%) < triclinic (23.7%) < monoclinic (60.7%).
Keywords: thio-ligands, Pt(II) complexes, structure, trans-effect, isomers