Inorg. Chem. 2003, 42, 7995−8002
Solvent-Dependent Dynamics of the MQ•fReII Excited-State Electron Transfer in [Re(MQ+)(CO)3(dmb)]2+ Davina J. Liard,† Cornelis J. Kleverlaan,‡ and Antonı´n Vlcˇek, Jr.*,† Department of Chemistry, Queen Mary and Westfield College, UniVersity of London, Mile End Road, London E1 4NS, United Kingdom, and Institute of Molecular Chemistry, UniVersiteit Van Amsterdam, Nieuwe Achtergracht 166, NL-1018 WV Amsterdam, The Netherlands Received June 9, 2003
The RefMQ+ MLCT excited state of [Re(MQ+)(CO)3(dmb)]2+ (MQ+ ) N-methyl-4,4′-bipyridinium, dmb ) 4,4′dimethyl-2,2′-bipyridine), which is populated upon 400-nm irradiation, was characterized by picosecond time-resolved IR and resonance Raman spectroscopy, which indicate large structural differences relative to the ground state. The RefMQ+ MLCT excited state can be formulated as [ReII(MQ•)(CO)3(dmb)]2+. It decays to the ground state by a MQ•fReII back-electron transfer, whose time constant is moderately dependent on the molecular nature of the solvent, instead of its bulk parameters: formamides ∼ DMSO ∼ MeOH (1.2−2.2 ns) < THF, aliphatic nitriles (3.2−3.9 ns)
