Metal oxos in chemistry and biology
The dianionic oxo ligand occupies a very special place in coordination chemistry, owing to its ability to donate pi electrons to stabilize high oxidation states of metals. The ligand field theory of multiple bonding in metal-oxos predicts that there must be an “oxo wall” between Fe-Ru-Os and Co-Rh-Ir in the periodic table. There have been many attempts to break down the wall, but in my seminar I will report that it is still standing! I will discuss the roles metal-oxos play in two of the most important chemical reactions on planet Earth, water oxidation to oxygen in photosystem II, and hydrocarbon oxygenation catalyzed by cytochrome P450.
Harry Gray is the Arnold O. Beckman Professor of Chemistry and the Founding Director of the Beckman Institute at the California Institute of Technology. After graduate work at Northwestern University and postdoctoral research at the University of Copenhagen, he joined the chemistry faculty at Columbia University, where in the early 1960s he developed ligand field theory to interpret the electronic structures of transition metal complexes. After moving to Caltech in 1966, he began work in inorganic photochemistry and biological inorganic chemistry that led to the development of light absorbers and robust catalysts for the production of solar fuels. In 1982, he and coworkers demonstrated that electrons can tunnel rapidly over long molecular distances through proteins, an experimental discovery that opened the way for theoretical work that shed light on the mechanisms of electron flow through molecular machines that function in respiration and photosynthesis. Gray has received the National Medal of Science (1986); the Wolf Prize (2004); the Welch Award (2009); six ACS national awards, including the Priestley Medal (1991); and 20 honorary doctorates. He is a member of the National Academy of Sciences and the Royal Society of Great Britain. He was Chairman of the Board of Directors of the Arnold and Mabel Beckman Foundation (2013-2015).