Mechanism of hydride donor generation using a Ru(II) complex containing an NAD+ model ligand: pulse and steady-state radiolysis studies.
Mechanism of hydride donor generation using a Ru(II) complex containing an NAD+ model ligand: pulse and steady-state radiolysis studies.
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DOI：
10.1021/ic702139n
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发表时间：
2008-03
影响因子：
4.6
通讯作者：
Dmitry E. Polyansky;D. Cabelli;J. Muckerman;T. Fukushima;Koji Tanaka;E. Fujita
中科院分区：
文献类型：
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作者：
Dmitry E. Polyansky;D. Cabelli;J. Muckerman;T. Fukushima;Koji Tanaka;E. Fujita
研究了[Ru(bpy)2(pbn)]（2+）在水溶液中形成nadh样[Ru(bpy)2(pbnHH)]（2+）的机理途径。由于溶剂化电子的还原(k=3.0 × 10(10) M（-1) s(-1)）或CO2(*-) (k=4.6 × 10(9) M（-1) s(-1)）或1,4-重氮双环[2.2.2]辛烷(k=1.1 × 10(9) M（-1) s(-1)）对MLCT激发态的还原猝灭(k=1.1 × 10(9) M(-1) s(-1))，形成单电子还原物质，然后是还原物质的质子化（p k= 11）。单还原质子化产物[Ru(bpy)2(pbnH(*))]（2+）的二聚化(k7a=2.2 × 10(8) M(-1) s(-1))，其次是二聚体的歧化以及单还原质子化产物和非质子化产物(k8= 1.2 × 10(8) M（-1) s(-1)）之间的交叉反应，形成最终的[Ru(bpy)2(pbnHH)]（2+）产物和等量的起始配合物[Ru(bpy)2(pbn)]（2+）。在0.2℃时，观察到一种二聚体中间体，很可能是pi堆叠二聚体，热分解形成[Ru(bpy)2(pbnHH)]（2+）和[Ru(bpy)2(pbn)](2+) （pH9）的等摩尔混合物，表明歧化是通过电子转移和质子转移的逐步途径发生的。
The mechanistic pathways of formation of the NADH-like [Ru(bpy) 2(pbnHH)] (2+) species from [Ru(bpy)2(pbn)](2+) were studied in an aqueous medium. Formation of the one-electron-reduced species as a result of reduction by a solvated electron (k=3.0 x 10(10) M(-1) s(-1)) or CO2(*-) (k=4.6 x 10(9) M(-1) s(-1)) or reductive quenching of an MLCT excited state by 1,4-diazabicyclo[2.2.2]octane (k=1.1 x 10(9) M(-1) s(-1)) is followed by protonation of the reduced species (p K a = 11). Dimerization (k7a=2.2 x 10(8) M(-1) s(-1)) of the singly reduced protonated species, [Ru(bpy) 2(pbnH(*))](2+), followed by disproportionation of the dimer as well as the cross reaction between the singly reduced protonated and nonprotonated species (k8= 1.2 x 10(8) M(-1) s(-1)) results in the formation of the final [Ru(bpy)2(pbnHH)](2+) product together with an equal amount of the starting complex, [Ru(bpy)2(pbn)](2+). At 0.2 degrees C, a dimeric intermediate, most likely a pi-stacking dimer, was observed that decomposes thermally to form an equimolar mixture of [Ru(bpy)2(pbnHH)](2+) and [Ru(bpy)2(pbn)](2+) (pH9) indicates that disproportionation occurs by a stepwise pathway of electron transfer followed by proton transfer.