Synthesis, molecular dynamics, and reactivity of mixed-metal clusters

Various mixed-metal tetranuclear clusters have been prepared by the combination of a carbonylmetalate with a closed metal carbonyl trimer. The cluster included Fe, Ru, Os, and Co in various combinations. Since transition-metal cluster compounds are currently being examined as catalysts for a variety of reactions involving CO, the reactions of mixed-metal clusters with CO were examined. It was found that most of the clusters studied fragmented in the presence of CO under mild conditions. Results of kinetic studies of the reactions are presented. The cluster compounds were found to react with tertiary phosphines and phosphites to yield mono- and di-substituted clusters. Isomeric products were also found to result from the reaction of the cluster compounds with internal alkynes with hydrogen evolved during the reaction. Results of studies of the molecular dynamics of the series of clusters H/sub 2/FeRu/sub 3/(CO)/sub 13/, H/sub 2/FeRu/sub 2/Os(CO)/sub 13/ and H/sub 2/FeRuOs/sub 2/(CO)/sub 13/ in which Ru is progressively replaced by Os are reported, and several different fluxional processes were observed. The /sup 13/C NMR spectra of these carbonyls are reported. (BLM)