QUATERNIZATION OF THE BRIDGEHEAD NITROGEN IN SILATRANYLOSMIUM(II) COMPLEXES AND REESTABLISHMENT OF THE TRANSANNULAR N-SI BOND FOLLOWING MIGRATORY INSERTION OF THE SILATRANYL LIGAND

The Si-N distance in the five-coordinate silatranyl complex Os(Si{OCH2 CH2}(3)N)Cl(CQ)(PPh3)(2) (1a, Q = O) is very long, and the geometry ab out nitrogen is planar. Accordingly, the nitrogen atom readily undergo es methylation, or protonation, and this increases the Si-N separation even further. On addition of CO to 1b (O = S), the coordinated CS ins erts into the Os-Si bond and the normal silatrane N-Si interaction is restored in, the product, Os(eta(2)-C{S}Si{OCH2CH2}(3)N)Cl(CO)(PPh3)(2 ) (4).