Metallacyclic complexes with ortho-stannylated triphenylphosphine ligands, LnOs(κ2(Sn,P)-SnMe2C6H4PPh2), derived from thermal reactions of the five-coordinate complex, Os(SnMe3)Cl(CO)(PPh3)2

Heating the five-coordinate trimethylstannyl complex, Os(SnMe3)Cl(CO)(PPh3)2, in solution with triphenylphosphine induces an ortho-stannylation of one phenyl group of a triphenylphosphine ligand and an ortho-metallation of another triphenylphosphine ligand, to produce the metallacyclic complexes, Os(κ2(Sn,P)-SnMeClC6H4PPh2)(κ2(C,P)-C6H4PPh2)(CO)(PPh3) (1) and Os(κ2(Sn,P)-SnMe2C6H4PPh2)(κ2(C,P)-C6H4PPh2)(CO)(PPh3) (2), suggesting the possible intermediacy of a complex with a coordinated stannylene ligand. Spectroscopic data indicate that only one diastereomer of 1 is formed and crystal structure determination of 1 reveals that this is the diastereomer with chloride directed towards the CO ligand. Complex 2 is converted to 1 through a redistribution reaction with SnMe2Cl2. Heating the six-coordinate trimethylstannyl complex, Os(SnMe3)Cl(CO)2(PPh3)2, in solution produces the osmium(II) methyl complex, Os(Me)(SnMe2Cl)(CO)2(PPh3)2 (3), through an exchange of methyl and chloride groups on the tin and osmium. In this rearrangement, the relative locations of the two CO ligands and the two PPh3 ligands remains unchanged. However, when the six-coordinate trimethylstannyl complex, Os(SnMe3)Cl(CO)2(PPh3)2 is heated under CO, the same exchange reaction is observed but the mono-triphenylphosphine, tricarbonyl complex, Os(Me)(SnMe2Cl)(CO)3(PPh3) (4), is produced and here the SnMe2Cl ligand is located trans to the PPh3 ligand. Crystal structure determinations for 1, 2, 3, and 4 have been obtained.