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Author Bromberg, S. E. ♦ Lian, T. ♦ Bergman, R. G. ♦ Harris, C. B.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CHEMISTRY ♦ PHYSICS ♦ IRIDIUM COMPLEXES ♦ PHOTOCHEMICAL REACTIONS ♦ RHODIUM COMPLEXES ♦ CHEMICAL BONDS ♦ ACTIVATION ENERGY ♦ DYNAMICS ♦ SOLUTIONS ♦ CYCLOALKANES ♦ ULTRAVIOLET RADIATION ♦ ENERGY-LEVEL TRANSITIONS ♦ QUANTUM EFFICIENCY
Abstract Using picosecond transient absorption spectroscopy we have examined the dynamics of Cp{sup *}Ir(CO){sub 2} (Cp{sup *}=C{sub 5}Me{sub 5}) in cyclohexane and Cp{sup *}Rh(CO){sub 2} in n-pentane solution at room temperature following 295-nm UV excitation. A transient absorption with an instrument limited risetime was observed for Ir from 440 to 740 nm and Rh from 500 to 650 nm. Each transient can be well fit to a biexponential decay consisting of a fast component of 2-3 ps and a slower component of 30-40 ps. These transients are attributed to excited state absorptions. Taking into account independent femtosecond IR studies of the ground state recovery and our data, we suggest that most excited state molecules relax through nondissociative excited states, decaying to the ground state without the loss of CO. These results offer an explanation for the low C-H bond activation quantum yields observed on preparative irradiation of Cp{sup *}Ir(CO){sub 2} and Cp{sup *}Rh(CO){sub 2}. 18 refs., 4 figs., 2 tabs.
ISSN 00027863
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-02-28
Publisher Place United States
Journal Journal of the American Chemical Society
Volume Number 118
Issue Number 8


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