[3+2] versus [2+2] Addition of Metal Oxides Across CC Bonds. Reconciliation of Experiment and Theory

Dirk V. Deubel studied chemistry at the universities of Kaiserslautern and Erlangen-Nürnberg, Germany. He received his Ph.D. from the Philipps Universität Marburg in 2000, where he worked with Prof. Dr. Gernot Frenking. He visited the Swiss Federal Institute of Technology, ETH Zürich, Switzerland, the University of Calgary, Canada, and Academia Sinica, Taiwan. Then he moved to the Swiss Center for Scientific Computing, CSCS, to continue the work on his Habilitation. His current research is strongly interdisciplinary. Major topics are quantum chemical studies of oxygen-transfer catalysis and metals in medicine.

Gernot Frenking studied chemistry at the universities Aachen, Kyoto, and TU Berlin, where he received his Ph.D. in 1979. After obtaining his Habilitation in Theoretical Organic Chemistry at the TU Berlin in 1984, he moved to the USA. Following one year as a visiting scientist in the group of Professor Henry F. Schaefer, III, at the University of California (Berkeley), he became a senior scientist at the Stanford Research Institute (SRI International) in Menlo Park, California. In 1989 he returned to Germany and became an Associate Professor for Computational Chemistry at the Philipps Universität Marburg. In 1998 he was appointed Full Professor for theoretical chemistry. His current research interests lie in the field of theoretical inorganic chemistry. Major topics are the nature of the chemical bond in inorganic compounds, particularly in transition metal complexes, and reaction mechanisms of transition metal catalyzed reactions.

The reaction of a metal oxide with a double bond is the initial step in the osmium-catalyzed cis-dihydroxylation of olefins. The mechanism of the addition of osmium tetraoxide and rhenium(VII) oxides across CC bonds was controversial. Early work indicated a [3+2] addition, and later kinetic studies suggested an initial [2+2] addition, whereas recent quantum-chemical calculations showed the [3+2] addition to be favored. Experiment and theory have now become reconciled. In this Account, we discuss recent contributions to the mechanistic debate as well as future challenges.