Synthesis, structure, and reactivity of low valent ruthenium complexes bearing bis(imino)pyridyl ligands

Over the past decade, late transition metal complexes bearing 2,6-bis(imino)pyridyl ligands, [N3], and other pincer type complexes have gained increasing attention due to their use in catalysis and in other chemical transformations. This thesis describes the synthesis, characterization, and reactivity of a series of [N3] ruthenium(0) complexes containing arene, dinitrogen, phosphine, and carbonyl ligands. Reduction of [N3]RuCl2(C 2H4) with hydridosilanes in an arene solvent yields new 18e - [N3]Ru(eta6-arene) complexes in which the [N3] ligand is bidentate. The arene ligand can be displaced with dinitrogen to yield the dimeric four-coordinate 16e- Ru(0) complex, {[N3]Ru}2(mu-N2), the first structurally characterized Ru(0) dinitrogen complex. Treatment of the low valent complexes with donor and pi-acceptor ligands generates five-coordinate Ru(0) complexes, [N3]RuL2 (L2 = (C2H4)2, (PMe3)2, (CO)2, (PMe3)(CO)).;The [N3]Ru(0) complexes exhibit high reactivity towards a variety of organic and main group substrates. Reaction of dinitrogen complex, {[N3]Ru}2(mu-N2), with dihydrogen yields the interesting binuclear paramagnetic Ru(I) dinitrogen complex, {[N 3]RuH}2(mu-N2), which has been spectroscopically and structurally characterized. Treatment of [N3]Ru(eta 6-arene) with H2 in the absence of nitrogen yields a diamagnetic Ru hydride species which is active for the catalytic hydrogenation of arenes. The [N3]Ru(0) complexes also react with organosilicon hydrides to yield a variety of silyl and silylene complexes, many of which are implicated in various catalytic processes as well other bond forming transformations.