Reaction of Molybdenocene and Tungstenocene Derivatives with the Divalent Silicon Species SiN^tBuCHCHN^tBu and (C₅Me₅)₂Si

The divalent organosilicon compounds (C₅Me₅)₂Si (Cp*₂Si) and (SiL^N₂) have been compared concerning their reactivity toward metallocene derivatives of molybdenum and tungsten. While Cp*₂Si does not react with Cp₂MH₂ (M = Mo, W), either thermally or photochemically, the reaction of SiL^N₂ with Cp₂MH₂ leads via silanediyl insertion to Cp₂M(H)(SiL^N₂H) (M = Mo (1a), W (1b)). Irradiation of a mixture of Cp₂Mo(PEt₃) and Cp*₂Si yields only decomposition products, whereas photolysis of equimolar amounts of Cp₂Mo(PEt₃) and SiL^N₂ results in the formation of the silanediyl complex Cp₂Mo(SiL^N₂) (2). 2 is extremely moisture sensitive and easily adds one molecule of water to yield the metallosilanol Cp₂Mo(H)(SiL^N₂OH) (3). 1a and 2 have been characterized by X-ray crystallography. 2 is the first molybdenum silanediyl complex with a tricoordinated silicon atom. The silicon−molybdenum interaction in 2 has to be described as a dative bond from the silicon to the metal atom.