Halide-promoted carbonylation of the imido ligand in osmium cluster Os3(.mu.3-NPh)(CO)10

Abstract

The imido cluster Os{sub 3}({mu}{sub 3}-NPh)(CO){sub 10} has been found to react with halides to give the isomeric clusters [PPN][Os{sub 3}({mu}{sub 3}-NPh)({mu}{sub 3}-NPh)({mu}{sub 2}-X)(CO){sub 9}] (7) and [PPN][Os{sub 3}({mu}{sub 3}-NPh)(X)(CO){sub 9}] (8), which have bridging and terminal halide ligands, respectively, with the ratio of the isomers dependent upon the halide used. For chloride, the major isomer is 7, which has been crystallographically shown to have two Os-Os bonds and the chloride ligand bridging two nonbonded Os atoms. For iodide, the major isomer is 8, which has three Os-Os bonds and a terminal iodide ligand. both isomers are present in nearly equal amounts when X = Br. The parent imido cluster Os{sub 3}({mu}{sub 3}-NPh)(CO){sub 10} is inert to carbonylation, but when the isomeric halide-substituted clusters are placed under 1 atm of CO at 22{degree}C, slow carbonylation occurs to form the two new clusters [Os{sub 3}-({eta}{sup 2}-{mu}{sub 3}-PhNCO)({mu}{sub 2}-X)(CO){sub 9}]{sup {minus}}(12) and [Os{sub 3}({eta}{sup 2}-{mu}{sub 2}-PhNCO)({mu}{sub 2}-X)(CO){sub 10}]{sup {minus}}(13), which possess bridging PhNCO ligands resulting from the insertion of CO into the Os-N bond. When left under CO, these clusters further carbonylated to release free PhN{double_bond}C{double_bond}O and form the known compounds [Os{sub 3}(X)(CO){sub 11}]{sup {minus}}. The oxygen atom of the {eta}{sup 2}-{mu}{submore » 2}-PhNCO ligand in 13 can be protonated and alkylated with CF{sub 3}CO{sub 2}H and CF{sub 3}SO{sub 3}CH{sub 3}, respectively, to give the clusters Os{sub 3}({eta}{sup 2}-{mu}{sub 2}-PhNCOR)({mu}{sub 2}-X)(CO){sub 10}(R = H, Me; X = Cl, I), of which the R = Me, X = I derivative has been crystallographically characterized. 27 refs., 6 figs., 10 tabs.« less