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- Title
Photochemistry of fac-[Re(bpy)(CO)<sub>3</sub>Cl].
- Authors
Sato, Shunsuke; Matubara, Yasuo; Koike, Kazuhide; Falkenström, Magnus; Katayama, Tetsuro; Ishibashi, Yukihide; Miyasaka, Hiroshi; Taniguchi, Seiji; Chosrowjan, Haik; Mataga, Noboru; Fukazawa, Naoto; Koshihara, Shinya; Onda, Ken; Ishitani, Osamu
- Abstract
The photochemistry of fac-[Re(bpy)(CO)3Cl] ( 1 a; bpy=2,2′-bipyridine) initiated by irradiation using <330 nm light has been investigated. Isomerization proceeded in THF to give the corresponding mer-isomer 1 b. However, in the presence of a small amount of MeCN, the main product was the CO-ligand-substituted complex ( OC-6-24)-[Re(bpy)(CO)2Cl(MeCN)] ( 2 c; bpy=2,2′-bipyridine). In MeCN, two isomers, 2 c and its ( OC-6-34) form ( 2 a), were produced. Only 2 c thermally isomerized to produce the ( OC-6-44) form 2 b. A detailed investigation led to the conclusion that both 1 b and 2 c are produced by a dissociative mechanism, whereas 2 a forms by an associative mechanism. A comparison of the ultrafast transient UV-visible absorption, emission, and IR spectra of 1 a acquired by excitation using higher-energy light (e.g., 270 nm) and lower-energy light (e.g., 400 nm) gave detailed information about the excited states, intermediates, and kinetics of the photochemical reactions and photophysical processes of 1 a. Irradiation of 1 a using the higher-energy light resulted in the generation of the higher singlet excited state with τ≤25 fs, from which intersystem crossing proceeded to give the higher triplet state (3HES( 1)). In THF, 3HES( 1) was competitively converted to both the triplet ligand field (3LF) and metal-to-ligand charge transfer (3 MLCT) with lifetimes of 200 fs, in which the former is a reactive state that converts to [Re(bpy)(CO)2Cl(thf)]+ ( 1 c) within 10 ps by means of a dissociative mechanism. Re-coordination of CO to 1 c gives both 1 a and 1 b. In MeCN, irradiation of 1 a by using high-energy light gives the coordinatively unsaturated complex, which rapidly converted to 2 c. A seven-coordinate complex is also produced within several hundred femtoseconds, which is converted to 2 a within several hundred picoseconds.
- Publication
Chemistry - A European Journal, 2012, Vol 18, Issue 49, p15722
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201202734