Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Advanced Chemical Technology Center in Kyoto (ACT-Kyoto), 105 Jibucho, Fushimi-ku, Kyoto 612-8374 (Japan).
Angew Chem Int Ed Engl. 2014 Oct 27;53(44):11813-7. doi: 10.1002/anie.201406553. Epub 2014 Sep 8.
The selective formation of dialkyl formamides through photochemical CO2 reduction was developed as a means of utilizing CO2 as a C1 building block. Photochemical CO2 reduction catalyzed by a Ru(bpy)2(CO)2 (bpy: 2,2'-bipyridyl)/Ru(bpy)3/Me2NH/Me2NH2(+) system in CH3CN selectively produced dimethylformamide. In this process a ruthenium carbamoyl complex (Ru(bpy)2(CO)(CONMe2)) formed by the nucleophilic attack of Me2NH on Ru(bpy)2(CO)2 worked as the precursor to DMF. Thus Me2NH acted as both the sacrificial electron donor and the substrate, while Me2NH2(+) functioned as the proton source. Similar photochemical CO2 reductions using R2NH and R2NH2(+) (R = Et, nPr, or nBu) also afforded the corresponding dialkyl formamides (R2NCHO) together with HCOOH as a by-product. The main product from the CO2 reduction transitioned from R2NCHO to HCOOH with increases in the alkyl chain length of the R2NH. The selectivity between R2NCHO and HCOOH was found to depend on the rate of Ru(bpy)2(CO)(CONR2) formation.
通过光化学 CO2 还原选择性地形成二烷基甲酰胺，被开发为利用 CO2 作为 C1 构建块的一种手段。Ru(bpy)2(CO)2（bpy：2,2'-联吡啶）/Ru(bpy)3/Me2NH/Me2NH2(+) 体系催化的光化学 CO2 还原在 CH3CN 中选择性地产生二甲基甲酰胺。在这个过程中，Me2NH 对Ru(bpy)2(CO)2的亲核攻击形成的钌氨基甲酰配合物(Ru(bpy)2(CO)(CONMe2))作为 DMF 的前体。因此，Me2NH 既充当牺牲电子供体，又充当底物，而 Me2NH2(+) 则充当质子源。使用 R2NH 和 R2NH2(+)（R = Et、nPr 或 nBu）进行类似的光化学 CO2 还原也得到了相应的二烷基甲酰胺（R2NCHO）和 HCOOH 作为副产物。随着 R2NH 烷基链长度的增加，CO2 还原的主要产物从 R2NCHO 转变为 HCOOH。R2NCHO 和 HCOOH 之间的选择性取决于Ru(bpy)2(CO)(CONR2)形成的速率。
