The first imido complex of osmium(VI), [CpOs(NH)(CH2SiMe3)2][SO3CF3]

Protonation of Os(eta(5)-C5H5)(N)(CH2SiMe3)(2) with either HBF4 or CF3SO3H at low temperature produces a thermally unstable imido, complex, [OS(eta(5)-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(eta(5)-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.