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 thro ugh its amino and deprotonated hydroxamate nitrogen atoms, has been sy nthesised. Reaction of this with HCl in aqueous solution produced crys tals of trans-dichlorobis(glycine) platinum(II) dihydrate, trans-PtCl2 (glyOH)(2) . 2H(2)O, resulting from hydrolysis of the glycinehydroxama te 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 interm olecular hydrogen bonding in the crystal gives rise to a layer structu re and each water molecule is involved in three hydrogen bonds. The co mplex 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-dichlor obis(glycinato)platinum (IV), trans,trans-PtCl2(glyO)(2). The crystal and molecular structures of this complex, one of the very few known pl atinum(IV)-amino acid complexes, have also been determined. The comple x is octahedral with both glycinates and chlorides bonded trans to one another. In the crystal there are two chemically identical but crysta llographically distinct molecules each of which occupies a special pos ition in the crystallographic inversion centre. The average bond dista nces in this complex are, Pt-Cl 2.305 Angstrom, Pt-N 2.051 Angstrom an d Pt-O 1.987 Angstrom. In the crystal there is extensive intermolecula r hydrogen bonding, each complex molecule hydrogen bonded to six other s giving a sheet-like structure.