The research proposed is a continuation of efforts to exploit the special features of the interaction of ruthenium amines and of osmium ammines with molecules of biological interest. These special features include the capacity to form robust complexes in oxidation states 2+ and 3+ for the metals. The change in oxidation state is a facile process, but it profoundly alters the way the metal ion affects the properties of the ligand. A prominent feature of the interaction of the lower oxidation state is the capacity of the metal to unload electron density on to the ligand; by contrast, in the higher oxidation state, the metal acts mainly as a Lewis acid, its capacity for this kind of interaction being somewhat enhanced by the single electron vacancy in the set of pi d orbitals. In the case of ruthenium, it is proposed to develop the basic chemistry of the cis and trans bisacetylacetone moieties, and to study the interaction of these species with the sample building blocks of complex molecules of biological interest. The substitution of ammonia by the anion of acetylacetone increases the electron density on the metal center, and reduces the charge on the ions. These differences affect the physical and chemical properties of the complexes, including their transport properties. The research on Os (NH3)52+ has revealed some novel effects which include the dihapto bonding of many unsaturated molecules (for example of aromatic hydrocarbons and heterocyclics) as well as facile room temperature processes involving cleavage of C-C, C-H, C-O and C-N bonds. The scope of this kind of reactivity is to be explored, with special emphasis on substrates which have some biological relevance.
