Breaking C-O Bonds with Uranium: Uranyl Complexes as Selective Catalysts in the Hydrosilylation of Aldehydes

We report herein the possibility to perform the hydrosilylation of carbonyls using actinide complexes as catalysts. While complexes of the uranyl ion [UO2](2+) have been poorly considered in catalysis, we show the potentialities of the Lewis acid [UO2(OTf)(2)] (1) in the catalytic hydrosilylation of a series of aldehydes. [UO2(OTf)(2)] proved to be a very active catalyst affording distinct reduction products depending on the nature of the reductant. With Et3SiH, a number of aliphatic and aromatic aldehydes are reduced into symmetric ethers, while (Pr3SiH)-Pr-i yielded silylated alcohols. Studies of the reaction mechanism led to the isolation of aldehyde/uranyl complexes, [UO2(OTf)(2)(4-Me2N-PhCHO)(3)], [UO2(mu-kappa(2)-OTf)(2)(PhCHO)](n), and [UO2(mu-kappa(2)-OTf(kappa(1)-OTf)(PhCHO)(2)](2), which have been fully characterized by NMR, IR, and single-crystal X-ray diffraction.