Speaker
Description
4d and 5d metal carbonyls are widely recognized for their photocatalytic C-H bond activation capabilities. UV excitation of these complexes leads to CO dissociation and the formation of a reactive metal center, which rapidly binds alkane C-H groups from solution and ultimately breaks the C-H bond. The reactivity of 3d metal carbonyls following photoinduced CO dissociation, however, is often hampered by the formation of triplet species, which instead are reactive towards Si-H bond activation. We have used ultrafast X-ray absorption spectroscopy and resonant inelastic X-ray scattering at the transition metal L-edge to access and evaluate the valence electronic structure locally at the reactive metal center all the way from the initial femtosecond excited-state and dissociation dynamics to pico- to-nanosecond bond activation. We find previously undetected species and characterize how their transient electronic structure dictates catalytic function on ultrafast timescales. We experimentally access, to the best of our knowledge for the first time, the essential charge-transfer orbital interactions, which make metal carbonyls reactive and which determine how they bind and break incoming C-H or Si-H bonds.
