Synthesis and Characterization of bis-(Diimine)-Carbonyl- Osmium(II) Pyridine and Triarylphosphine Complexes
Elise G. Megehee, Department of Chemistry, St. John’s College of Liberal Arts and Sciences
Osmium metal complexes are of interest as they exhibit visible luminescence upon excitation with visible or ultraviolet light and as such are possible models of photosynthetic reaction center, possible energy and electron transfer agents, and possible photochemical or electrochemical reaction catalysts. Over the past few years, my students and I have synthesized numerous complexes with a variety of ligands to explore the generality of the osmium triflate intermediate and to study how ligand variations affect the electronic properties of the systems. All of these complexes contain the bis-(diimine)-carbonyl osmium(II) moiety and use a triflate intermediate as the starting point for this chemistry. Recently we have synthesized a series of pyridine and triphenylphosphine osmium complexes of nine substituted diimines. We will discuss the synthesis and characterization of these compounds by cyclic voltammetry, 1H, 13C, 31P NMR, infrared, UV-visible absorbance and emission spectroscopies as well as time resolved emission lifetime studies. We will discuss our conclusions about the effect of this ligand variation on the electronic properties of these compounds.