PHOTOCHEMICAL AND ELECTROCHEMICAL REDUCTION OF CARBON-DIOXIDE TO CARBON-MONOXIDE MEDIATED BY (2,2'-BIPYRIDINE)TRICARBONYLCHLORORHENIUM(I) AND RELATED COMPLEXES AS HOMOGENEOUS CATALYSTS
PHOTOCHEMICAL AND ELECTROCHEMICAL REDUCTION OF CARBON-DIOXIDE TO CARBON-MONOXIDE MEDIATED BY (2,2'-BIPYRIDINE)TRICARBONYLCHLORORHENIUM(I) AND RELATED COMPLEXES AS HOMOGENEOUS CATALYSTS
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DOI：
10.1002/hlca.19860690824
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发表时间：
1986-01-01
影响因子：
1.8
通讯作者：
ZIESSEL, R
中科院分区：
文献类型：
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作者：
HAWECKER, J;LEHN, JM;ZIESSEL, R
[fac-Re（bpy）（CO）3Cl]（bpy= 2，2“-bipyridine）是一种高效的均相催化剂，可用于CO2的选择性和持续的光化学或电化学还原，在过量Cl-存在下，量子产率为14%，法拉第效率为98%。光化学过程发生在可见光照射下，并消耗叔胺作为电子供体。在不存在过量Cl-离子的情况下，分离出甲酸根-乙二胺络合物。用Cl-离子取代产生游离甲酸盐，但没有检测到CO。发光测量表明，叔胺通过还原机理猝灭了双金属络合物的金属-配体电荷转移激发态，速率常数为3.4 × 10 - 4。107 M-1 S-1光化学或电化学产生的19e-络合物[Re（bpy）（CO）3X]似乎是CO生成过程中的活性前体。对来自13 C富集CO2的13 C富集的羰基-二氢呋喃和甲酸-二氢呋喃络合物进行了详细的光谱研究，以确认产物的来源并研究配体的交换。本CO2光还原过程的一种机制，它涉及单独的途径CO和甲酸的产生，其中[Re（bpy）（CO）3X]配合物的光活性和催化中心的作用。
[fac-Re(bpy) (CO)3Cl] (bpy=2,2''-bipyridine) is an efficient homogeneous catalyst for the selective and sustained photochemical or electrochemical reduction of CO2 to CO. A quantum yield of 14% and a faradic efficiency of 98% were measured in the presence of excess Cl- ions. The photochemical process took place under visible-light irradiation and consumed a tertiary amine as electron donor. A formato-rhenium complex was isolated in the absence of excess Cl- ions. Substitution by Cl- ion generated free formate, but no CO was detected. Luminescence measurements showed that the teritary amine quenches the metal-to-ligand charge-transfer excited state of the rhenium complex via a reductive mechanism, with a rate constant of 3.4 .times. 107 M-1 s-1. The 19e-complex [Re(bpy)(CO)3X]- produced either photochemically or electrochemically appears to be the active precursor in the CO-generation process. Detailed spectroscopic studies on 13C-enriched carbonyl-rhenium and formato-rhenium complexes derived from 13C-enriched CO2 were performed in order to confirm the origin of the products and to study the exchange of the ligands. A mechanism for the present CO2 photoreduction process is presented; it involves separate pathways for CO and formate generation, in which the [Re(bpy)(CO)3X] complex plays the role of both the photoactive and the catalytic center.