An Efficient Iridium Catalyst for Reduction of Carbon Dioxide to Methane with Trialkylsilanes

作者：Sehoon Park, David Bézier, Maurice Brookhart · 发表于：Journal of the American Chemical Society · 年份：2012 · DOI：10.1021/ja305318c · 被引用次数：256 · 研究领域：Carbon dioxide utilization in catalysis、Organoboron and organosilicon chemistry、CO2 Reduction Techniques and Catalysts

Cationic silane complexes of general structure (POCOP)Ir(H)(HSiR(3)) {POCOP = 2,6-[OP(tBu)(2)](2)C(6)H(3)} catalyze hydrosilylations of CO(2). Using bulky silanes results in formation of bis(silyl)acetals and methyl silyl ethers as well as siloxanes and CH(4). Using less bulky silanes such as Me(2)EtSiH or Me(2)PhSiH results in rapid formation of CH(4) and siloxane with no detection of bis(silyl)acetal and methyl silyl ether intermediates. The catalyst system is long-lived, and 8300 turnovers can be achieved using Me(2)PhSiH with a 0.0077 mol % loading of iridium. The proposed mechanism for the conversion of CO(2) to CH(4) involves initial formation of the unobserved HCOOSiR(3). This formate ester is then reduced sequentially to R(3)SiOCH(2)OSiR(3), then R(3)SiOCH(3), and finally to R(3)SiOSiR(3) and CH(4).