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- Thursday, January 28, 1993
- Cluster vs. non-cluster catalysis in olefin thermal hydrosilylation and isomerization reactions using Ru3(CO)12
- Published at:Not Found
H. S. Hilal*, Shukri Khalaf and Waheed Jondi,J. Organometal. Chem., 452( 1993)167-173
Abstract
The ruthenium cluster Ru$CO)~~ (1) has been evaluated as a catalyst precursor for the thermal reactions of l-octene with
(EtO),SiH in a mixture of dioxane and benzene at temperatures of 50-75°C. At 70°C or higher, olefin isomerization and
hydrosilylation reactions were observed; the products,
tram-Zoctene and CsHIICH2CHZCH,Si(OEt), (2) were identified. The
reactions were accompanied by a side reaction that involved generation of hydrogen gas. The sum of the rates of appearance of 2
and H, equalled the rate of disappearance of (EtO),SiH. No significant isomerization was observed in the absence of (EtO),SiH.
Maximum turnover number values of 7.50, 70, and 70 were obtained for isomerization, hydrosilylation, and H, production
reactions, respectively. At WC or lower, no hydrosilylation or hydrogen production was observed, and the only product was
trans-2-octene. No detectable disappearance of (EtO),SiH was observed. Acetophenone was also hydrosilated by use of cluster
1,
as catalyst; the only product obtained was (EtO),SiOC(PhXHXCH,). Kinetic studies indicated that the reactions of 1-octene and
the reaction of acetophenone involved a catalytically active species of lower nuclearity. There was evidence of concurrent cluster
catalysis, especially during the first few minutes of the reaction.
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Hikmat S. Hilal