Femtosecond IR studies of alkane C-H bond activation
- Lawrence Berkeley National Lab., CA (United States); and others
In this paper, we report the first femtosecond time resolved IR spectroscopic study of the mechanism of alkane C-H bond activation reaction by organometallic compounds. Taking advantage of the high C-H bond activation quantum yield of Tp*Rh(CO){sub 2} (Tp*=HB-Pz{sub 3}*, Pz*=3,5- dimethylpyrazolyl), we have observed two subsequently formed reactive monocarbonyl intermediates in room temperature alkane solution. We assign the intermediate at 1972 cm{sup -1} as an initially formed solvated complex which then undergoes intramolecular rearrangement in 200 ps to form a more stable solvated species at 1990 cm{sup -1}. This latter complex may be the commonly invoked {sigma}-complex, which goes on to activate the C-H bond in ca. 500 ns, corresponding to a free energy of activation {Delta}G{ne}= 8.9 kcal/mol. Both the detailed structures of the intermediates and the bond selectivity of C-H activation reactions are being studied in on-going experiments.
- OSTI ID:
- 539063
- Report Number(s):
- CONF-960807--
- Country of Publication:
- United States
- Language:
- English
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