562824-28-6Relevant articles and documents
A mechanistic dichotomy in scandium ion-promoted hydride transfer of an NADH analogue: Delicate balance between one-step hydride-transfer and electron-transfer pathways
Yuasa, Junpei,Yamada, Shunsuke,Fukuzumi, Shunichi
, p. 14938 - 14948 (2006)
The rate constant (kH) of hydride transfer from an NADH analogue, 9,10-dihydro-10-methylacridine (AcrH2), to 1-(p-tolylsulfinyl)-2,5-benzoquinone (TolSQ) increases with increasing Sc 3+ concentration ([Sc3+]) to reach a constant value, when all TolSQ molecules form the TolSQ-Sc3+ complex. When AcrH 2 is replaced by the dideuterated compound (AcrD2), however, the rate constant (kD) increases linearly with an increase in [Sc3+] without exhibiting a saturation behavior. In such a case, the primary kinetic deuterium isotope effect (kH/kD) decreases with increasing [Sc3+]. On the other hand, the rate constant of Sc3+-promoted electron transfer from tris(2- phenylpyridine)iridium [Ir(ppy)3] to TolSQ also increases linearly with increasing [Sc3+] at high concentrations of Sc3+ due to formation of a 1:2 complex between TolSQ?- and Sc 3+, [TolSQ?- (Sc3+)2], which was detected by ESR. The significant difference with regard to dependence of the rate constant of hydride transfer on [Sc3+] between AcrH2 and AcrD2 in comparison with that of Sc3+-promoted electron transfer indicates that the reaction pathway is changed from one-step hydride transfer from AcrH2 to the TolSQ-Sc3+ complex to Sc3+-promoted electron transfer from AcrD2 to the TolSQ-Sc3+ complex, followed by proton and electron transfer. Such a change between two reaction pathways, which are employed simultaneously, is also observed by simple changes of temperature and concentration of Sc3+.
