An Isolable NHC-Supported Silanone

The unique isotable silanone complex 3 has been synthesized and isolated in 94% yield by the remarkably facile oxygenation of the NHC-silylene precursor 2 featuring a Si(II) atom with unusually high nucleophilicity. The latter precursor is easily accessible by reaction of the stable silylene 1 with the corresponding N-heterocyclic carbene (NHC) at -60 degrees C. The remarkably short Si=O distance of 1.541(2) angstrom in 3 suggests the presence of a betaine-like Si=O pi system with balanced electrostatics.