The aim of this thesis has been to extend the understanding of the chemistry of dimethylplatinum complexes and in particular the synthesis of at aquadimethylplatinum(IV) complexes. From these complexes, a quantitative measure of the trans effect of a ligand coordinated in a platinum(IV) complex would be obtained.
The compounds cis-Pt(CH3)2L2 where L2 = bipy, py2, tmen (NH3)2, en, (dmso)2, NBD and (CN)2 have been prepared. This has extended the range of complexes of this type to now include amines and N-donors as ligands, but ligands of weaker donor capacity like O-donors would not coordinate to dimethylplatinum(II).
cis-Pt(CH3)2L2 with L2 = bipy, py2, tmen and NBD reacted with a variety of oxidising agents and these products have been characterised. The bispyridine and bipyridyl complexes were very reactive, reacting readily with alcohols, water and dichloromethane to produce platinum(IV) complexes. From the platinum(IV) products of these oxidative additions, fac-Pt(CH3)2X(OH2)3+ where X =CH3, CF3, CCl3, CH2Cl, OCH3, OCH2CH3, OH, CH2C6H5, Br, I, Cl, C(O)CH3 have been prepared.
Cyanide reacted with dimethylplatinum(IV) complexes to ultimately yield Pt(CH3)2(CN)42-. The intermediate complexes in these reactions have been characterised. Reductive elimination to platinum(II) cyanide complexes was more important for these complexes than with dimethylplatinum(IV) compexes with weaker donor ligands. U.V. irradiation accelerated the substitution reactions of platinum(IV) complexes compared to thermal substitution. The complex Pt(CH3)2(CN)(OH2)3+ was not obtained from these reactions as hoped. This was due to the insolubility of hydroxide oligomer [Pt(CH3)2(CN)(OH)]n.
Reactions of thiocyanate, nitrite and acetate with dimethylplatinum(IV) complexes were studied and solutions containing Pt(CH3)2X(OH2)3+ where X = SCN, NO2 were prepared.
The rates of exchange of water trans to methyl in Pt(CH3)2X(OH2)3+ with solvent water were measured by 17O N.M.R. spectroscopy. These rates showed only a small cis effect on the exchange rate. Attempts to obtain rate data of water exchange trans to X were not successful.
The rates of isomerisation of Pt(CH3)2X(gly)(OH2) were measured by 1H N.M.R. spectroscopy. These rates were dependent on the trans effect of X and showed a trans effect series CH3≫Br>Cl>OH2. The rates of isomerisation of the other isomers of Pt(CH3)2X(gly)(OH2) were also investigated and discussed in terms of cis effects.