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Kinetic and mechanistic investigation of the sequential hydrogenation of phenylacetylene catalyzed by OsHCl(CO)(PR sub 3 ) sub 2 (PR sub 3 = PMe-t-Bu sub 2 and P-i-Pr sub 3 )

Journal Article · · Journal of the American Chemical Society; (USA)
OSTI ID:6725144
; ; ;  [1]; ;  [2]; ;
  1. Universidad de Zaragoza (Spain)
  2. Universitaet Wuerzburg (Germany, F.R.)
The reactivities of the hydrido carbonyl complexes OsHCl(CO)(PR{sub 3}){sub 2} (PR{sub 3} = PMe-t-Bu{sub 2} (1), P-i-Pr{sub 3} (2)) toward hydrogen, alkynes, and oxygen have been studied. The solutions of 1 and 2 are rapidly decolorized upon contact with H{sub 2} under ambient conditions; the decolorized solution of 2 shows in benzene-d{sub 6} a {sup 1}H NMR spectrum that is consistent with the formation of the dihydrogen compound OsHCl({eta}{sup 2}-H{sub 2})(CO)(P-i-Pr{sub 3}){sub 2} (3). The reactivity of 1 and 2 toward alkynes depends on the type of alkyne used. The title complexes react with acetylene, propyne, and phenylacetylene by insertion to give the five-coordinate vinylosmium compounds Os(CH=CHR)Cl(CO)(Pr{sub 3}){sub 2} (7 and 8); the same starting materials in the presence of t-BuC{triple bond}CH and PhC{triple bond}CPh are completely inert. The kinetic investigation of this reaction provides evidence that indicates that the formation of styryl derivatives is the step that determines the selectivity for the hydrogenation to the alkene.
OSTI ID:
6725144
Journal Information:
Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 111:19; ISSN 0002-7863; ISSN JACSA
Country of Publication:
United States
Language:
English