HYDROCARBON C-H BOND ACTIVATION USING CATIONIC LATE TRANSITION METAL COMPLEXES
Robert G. Bergman
Department of Chemistry
University of California, Berkeley
In the early 1980's our group uncovered a low-valent iridium(I) system capable of converting alkanes into hydrido(alkyl)metal complexes by oxidative addition of hydrocarbon C-H bonds to the metal center. More recently we have found a higher-valent alkyliridium(III) system that also is capable of hydrocarbon C-H bond activation. This process has been used to prepare a number of interesting organometallic complexes, including those with hindered metal-carbon bonds, as well as cationic hydridocarbene and -carbyne complexes.
The C-H activation reactions involve overall metal alkyl/C-H s-bond metathesis, but evidence will be provided that the transformations proceed by initial C-H oxidative addition to give very high oxidation state iridium(V) intermediates. The synthesis of reactive hydridoiridium(III) complexes, and preliminary results on the use of these materials for low-temperature catalytic C-H activation reactions, will be presented.