Femtosecond time resolved infrared studies of Si-H bond activation

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:560375

Yang, H; Kotz, K T; Asplund, M; Bromberg, S E ^[1]

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1. Univ. of California, Berkeley, CA (United States)

We report the first time-resolved IR studies of the silane Si-H bond activation mechansim on time-scales from sub-picosecond to nanosecond. It has been accepted that the primary photochemical process following UV irradiation of {eta}{sup 5}-CpMn(CO){sub 3} [A] in room temperature solution is the loss of a CO ligand. By monitoring the time evolution of the CO stretching frequencies, we have observed three distinct pathways for the formation of the activated hydridosilyl complex {eta}{sup 5}-CpMn(CO){sub 2}(H)(SiEt{sub 3}) [B]: (1) direct formation after CO dissociation; (2) formation through an intermediate [C] whose lifetime is about 90 ps; and (3) formation through another intermediate [D] which can be assigned as a solvated dicarbonyl species that eventually rearranges to form B on a time-scale of > 1 ns. Considering possible chemical processes, we have tentatively assigned C as a ring-slipped {eta}{sup 3} species which changes its hapticity from {eta}{sup 3} to {eta}{sup 5} in {approximately}90 ps. Detailed structures of the intermediates are being studied using ab initio electronic structure calculations. Experiments that extend beyond 1 ns and those on Si-H bond activation by other metal complexes such as {eta}{sup 5}-CpRe (CO){sub 3} are underway.

• OSTI ID: 560375
• Report Number(s): CONF-970443--
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
CHEMICAL ACTIVATION
CHEMICAL BONDS
DISSOCIATION
ELECTRONIC STRUCTURE
HYDROGEN
IRRADIATION
SILANES
SILICON