Well-Defined Surface Tungstenocarbyne Complexes through the Reaction of [W(⋮CtBu)(CH2 tBu)3] with Silica

The molecular complex [W(⋮CtBu)(CH2 tBu)3], 1, reacts with SiO2 - (700) to give as major species 2a, [(⋮SiO)W(⋮CtBu)(CH2 tBu)2], while a bisgrafted surface species 3a, [(⋮SiO)2W(⋮CtBu)(CH2 tBu)], is obtained on SiO2 - (200). As in molecular organometallic chemistry, the alkylalkylidyne tautomeric form is favored. Despite these structural features, these surface organometallic complexes are very active olefin metathesis catalysts, as reported earlier, and it is very likely that the necessary metallocarbene intermediates are generated under the reaction conditions.