Clusters containing carbene ligands. 1. Novel transformations of carbene ligands at multinuclear metal sites. .alpha.-Activation of carbon-hydrogen and sulfur-carbon bonds in carbene containing thiolatotriosmium carbonyl cluster compounds

Abstract

Studies of transition-metal cluster compounds are revealing an increasing number of new and unusual ligand transformations that involve interactions at two or more metal sites. An understanding of the scope and mechanisms of these rearrangements will play a central role in developing the potential of these compounds to serve as reaction catalysts. In their recent studies they have discovered that the osmium cluster complex Os/sub 3/(CO)/sub 9/(..mu../sub 3/-CO)(..mu../sub 3/-S) will react with NMe/sub 3/ by a double C-H activation process to yield the product Os/sub 3/(CO)/sub 8/-(C(H)NMe/sub 2/)(..mu../sub 3/-S)(..mu..H)/sub 2/ which contains a terminally coordinated secondary aminocarbene ligand. This compound has been found to be a precursor for an effective catalyst for the exchange of alkyl groups in tertiary amines. They have now discovered that bis(dialkylamino)methanes can also serve as reagents for the introduction of secondary amino-carbene ligands into certain osmium cluster complexes and these engage in some very unusual and potentially important multicenter ligand transformations. These results are described in detail in this report.