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).

International audienceHydrosilylation with well defined piano-stool iron(II) complexes bearing both N-heterocyclic carbene and cyclopentadienyl ligands was accomplished with both aldehydes and ketones. Typically, the reduction of aldehydes exhibited good activities (full reduction at 30 °C in 3 h), whereas for ketones, the reaction need 16 h at 70 °C to obtain good conversions. Of notable interest is the use of visible light irradiation to generate one of the active catalyst

Although iron has been known and widely used in coordination and organometallic chemistry for decades and N‐heterocyclic carbenes (NHCs) have also been used for about half a century, their combination surprisingly did not become a hot topic in chemistry until this last decade. This review presents several recent and stimulating developments in homogeneous catalysis done mainly using iron/NHC‐based catalysts. Of particular interest are the roles of iron/NHC complexes in cross‐coupling Kochi reactions, CC bond formation reactions and hydrofunctionalization, and more particularly in hydrosilylation. Our review summarizes the key developments in these fields.