Highly Selective and Efficient Perdeuteration of n-Pentane via H/D Exchange Catalyzed by a Silica-Supported Hafnium-Iridium Bimetallic Complex.

A Surface OrganoMetallic Chemistry (SOMC) approach is used to prepare a novel hafnium-iridium catalyst immobilized on silica, HfIr/SiO 2 , featuring well-defined [≡SiOHf(CH 2 t Bu) 2 (μ-H) 3 IrCp*] surface sites. Unlike the monometallic analogous materials Hf/SiO 2 and Ir/SiO 2 , which promote n-pentane deuterogenolysis through C-C bond scission, we demonstrate that under the same experimental conditions (1 bar D 2 , 250 °C, 3 h, 0.5 mol %), the heterobimetallic catalyst HfIr/SiO 2 is highly efficient and selective for the perdeuteration of alkanes with D 2 , exemplified on n-pentane, without substantial deuterogenolysis (<2 % at 95 % conversion). Furthermore this HfIr/SiO 2 catalyst is robust and can be re-used several times without evidence of decomposition. This represents substantial advance in catalytic H/D isotope exchange (HIE) reactions of C(sp 3 )-H bonds.