The First Imido Complex of Osmium(VI), [CpOs(NH)(CH₂SiMe₃)₂][SO₃CF₃]

Protonation of Os(η⁵-C₅H₅)(N)(CH₂SiMe₃)₂ with either HBF₄ or CF₃SO₃H at low temperature produces a thermally unstable imido complex, [Os(η⁵-C₅H₅)(NH)(CH₂SiMe₃)₂][X] (X = BF₄, SO₃CF₃). The imido complex is a strong acid and readily deprotonates. A similar reaction between the nitridoosmium complex and [AuPPh₃][BF₄] forms a gold adduct, [Os(η⁵-C₅H₅)(NAuPPh₃)(CH₂SiMe₃)₂][BF₄]. Each of the two complexes has a three-legged piano stool molecular structure, but the Os−N distance in the imido ligand is longer than that in the gold adduct. Lewis bases displace (triphenylphosphine)gold from the osmium nitrido group.