Addition of NH3 to the cluster complexes M3H(mu-H)(CO)(11) (M = Ru, Os)

The reactions of ammonia with either Ru3H(mu-H)(mu-CO)(CO)(10) (I) or Os3H(mu-H)(CO)(11) (II) in CD2Cl2 solutions yield [NH4](+)[M-3(mu-H)(mu-CO)(CO)(10)](-) (M = Ru, Os). When the reactions are followed at low temperature (183 K) by means of H-1, C-13, and N-15 NMR spectroscopy, it is possible to detect the formation of kinetic products which are derived from the addition of an ammonia molecule to a carbonyl carbon atom. In the Ru case ammonia is bonded to the bridging carbonyl carbon atom and maintains its wholeness. In the Os system a carbamoyl moiety is formed by transfer of one hydrogen from NH3 to the oxygen atom of the carbonyl group to form an O-H bond. The NMR observation of the latter functionality is prevented by the occurrence of a fast proton exchange with the excess of free NH3 present. Two isomers of this carbamoyl-containing species can be detected; the structural difference between them is based only on which carbonyl has undergone the ammonia attack.