Sigma-bond activation reactions induced by unsaturated Os(IV)-hydride complexes

Abstract Unsaturated osmium(IV)-hydride complexes are diamagnetic six-coordinate d4 species, which undergo distortion from the octahedral geometry to form unusual D4d or C2v geometries. They display a notable ability to activate H H, B H, C H, C C, C O, C Br, Si H, Sn H, N H, or O H bonds of a wide range of inorganic, organic, and organometallic molecules, including: molecular hydrogen, boranes, phosphines, heterocycles, olefins, dienes, enynes, allenes, allenedienes, alkynamides, alkylhalides, silanes, stannanes, diamines, oximes, metal-nucleosides, or molecular oxygen. The activations yield, among other organometallic derivatives, dihydrogen, borane, borinium, alkylidene, alkylidyne, vinylidene, NHC, silylene, stannyl, osmafuran, osmaisobenzofuran, osmabenzimidazolium, or azavinylidene complexes. A characteristic of these activation processes is that they do not result in an increase of the formal oxidation state of the metal center. Given the wide range of σ-bond activations promoted by these compounds and the wide variety of complexes formed, future interesting applications for them can be anticipated.