SYNTHESIS OF TRANS-BIS(GLYCINEHYDROXAMATO)PLATINUM(II) HYDRATE AND TRANS-DICHLOROBIS(GLYCYLGLYCINE)PLATINUM(II) DIHYDRATE AND THE CRYSTAL AND MOLECULAR-STRUCTURES OF TRANS-DICHLOROBIS(GLYCINE)PLATINUM(II) DIHYDRATE AND TRANS,TRANS-DICHLOROBIS(GLYCINATO)PLATINUM(IV), HYDROLYSIS PRODUCTS FORMED IN REACTIONS OF THE FORMER COMPLEXES

The complex trans-bis(glycinehydroxamato) platinum(II) hydrate, trans-Pt(GHA)(2) . H2O, in which the ligand is coordinated to the metal through its amino and deprotonated hydroxamate nitrogen atoms, has been synthesised. Reaction of this with HCl in aqueous solution produced crystals of trans-dichlorobis(glycine) platinum(II) dihydrate, trans-PtCl2(glyOH)(2) . 2H(2)O, resulting from hydrolysis of the glycinehydroxamate ligand. The crystal and molecular structures show that the complex is square planar with the chloride ligands trans to each other, as are the glycine ligands which are N-coordinated. The Pt-Cl and Pt-N bond distances are 2.283 and 2.037 Angstrom, respectively. Extensive intermolecular hydrogen bonding in the crystal gives rise to a layer structure and each water molecule is involved in three hydrogen bonds. The complex trans-dichlorobis(glycylglycine) platinum(II) dihydrate was also prepared but attempts to oxidise it with H2O2 resulted in hydrolysis of the peptide ligand as well as oxidation, giving trans,trans-dichlorobis(glycinato)platinum (IV), trans,trans-PtCl2(glyO)(2). The crystal and molecular structures of this complex, one of the very few known platinum(IV)-amino acid complexes, have also been determined. The complex is octahedral with both glycinates and chlorides bonded trans to one another. In the crystal there are two chemically identical but crystallographically distinct molecules each of which occupies a special position in the crystallographic inversion centre. The average bond distances in this complex are, Pt-Cl 2.305 Angstrom, Pt-N 2.051 Angstrom and Pt-O 1.987 Angstrom. In the crystal there is extensive intermolecular hydrogen bonding, each complex molecule hydrogen bonded to six others giving a sheet-like structure.