Liard D J, Vlcek A
Department of Chemistry, Queen Mary and Westfield College, University of London, United Kingdom.
Inorg Chem. 2000 Feb 7;39(3):485-90. doi: 10.1021/ic990770f.
Excited-state dynamics of [Re(MQ+)(CO)3(dmb)]2+, (dmb = 4,4'-dimethyl-2,2'-bipyridine, MQ+ = N-methyl-4,4'-bipyridinium) was studied by femtosecond time-resolved spectroscopy in the visible spectral region. Excitation at 400 or 330 nm prepares a mixture of Re --> dmb and Re --> MQ+ metal-to-ligand charge-transfer, MLCT, states. The Re --> dmb MLCT state undergoes a dmb*- --> MQ+ interligand electron transfer to produce a relatively long-lived Re --> MQ+ MLCT excited state, which was characterized spectroscopically. The lifetime of this reaction was determined as 8.3 ps in CH3CN. The interligand electron transfer occurs as a nonadiabatic process in the Marcus normal region. The electronic coupling was estimated to lie in the range 20-40 cm(-1). The electron transfer becomes partially adiabatic in ethylene glycol solutions for which the reaction lifetime of 14.0 ps was determined. Depending on the medium relaxation time, the principal control of the electron-transfer rate changes from electron tunneling to solvent relaxation.
通过飞秒时间分辨光谱在可见光谱区域研究了[Re(MQ⁺)(CO)₃(dmb)]²⁺（dmb = 4,4'-二甲基-2,2'-联吡啶，MQ⁺ = N-甲基-4,4'-联吡啶鎓）的激发态动力学。在400或330 nm处激发会产生Re→dmb和Re→MQ⁺金属到配体电荷转移（MLCT）态的混合物。Re→dmb MLCT态经历dmb*→MQ⁺配体间电子转移，产生一个寿命相对较长的Re→MQ⁺ MLCT激发态，该激发态通过光谱进行了表征。在乙腈中该反应的寿命确定为8.3 ps。配体间电子转移在Marcus正常区域以非绝热过程发生。电子耦合估计在20 - 40 cm⁻¹范围内。在乙二醇溶液中电子转移变为部分绝热，确定其反应寿命为14.0 ps。根据介质弛豫时间，电子转移速率的主要控制因素从电子隧穿变为溶剂弛豫。
