THE SYNTHESIS AND PHOTOCHEMICAL CHARACTERIZATION OF CYCLOMETALLATED IRIDIUM AND RUTHENIUM COMPLEXES

This dissertation is a fusion of synthetic efforts to obtain materials with carbon-transition metal bonds and the thermal chemistry and photochemistry of such materials containing aromatic chelated ligands. An interest in preparing analogues to the "Watts" complex, Ir(N,N'-bpy)(,2)(N,C('3)-bpy)('2+) (bpy = 2,2'-bipyridine), led to reactions between iridium chloride with 2-phenylpyridine (Hppy) which gave the dimeric material Ir(ppy)(,2)Cl (,2) and traces of the monomeric triply orthometallated material fac-Ir(ppy)(,3). Subsequently an analogous dimer containing the orthometallating ligand 7,8-benzoquinoline (Hbzq) was made. Also monomeric derivatives of these dimers, a close cousin of the "Watts" complex, Ir(bpy)(,2)ppy('2+), and orthometallated ruthenium carbonyl species, were prepared to give an extensive set of complexes belonging to a class of luminescent materials containing aromatic carbon-metal bonds. The presence of the carbon-iridium bond imparts increased electron density to the metal relative to the structurally similar 2,2'-bipyridine and 1,10-phenanthroline complexes. As a result of this increased electron density on the iridium, these complexes reduce at more cathodic potentials and their oxidations are at less anodic potentials. Also the absorption and emission spectra show low energy metal to ligand charge transfer (MLCT) bands. Several of these materials have been shown to have excited state potentials of above 1 volt (vs SCE), which is sufficient energy to drive the water splitting reaction.;This dissertation describes photochemical, electrochemical, and some reaction chemistry of the orthometallated dimers of iridium containing 2-phenylpyridine and 7,8-benzoquinoline in chapter one; of the 2,2'-bipyridine and 1,1-phenanthroline derivatives in chapter two; of the triply orthometallated phenylpyridine system in chapter three; of the pyridine, phosphine, and carbon monoxide adducts to the phenylpyridine and benzoquinoline dimers, plus the mixed ligand complex Ir(ppy)(bpy)(,2)('2+) in chapter four; and of the ruthenium carbonyl complexes orthometallated with phenylpyridine and benzoquinoline in chapter five.