In:
European Journal of Inorganic Chemistry, Wiley, Vol. 2007, No. 31 ( 2007-11), p. 4973-4979
Abstract:
The influence of phosphane “arm‐on, arm‐off” association/dissociation in rhodium catalysed alkene hydrogenation using [Rh(COD)(κ 3 ‐triphos)]PF 6 { 1 , COD = cyclooctadiene, triphos = 1,1,1‐tris(diphenylphosphanylmethyl)ethane} has been investigated by comparison of the activity of 1 to mixtures of the related diphosphane complex, [Rh(COD)(κ 2 ‐dppp)]PF 6 { 2 , dppp = 1,3‐bis(diphenylphosphanyl)propane} and triphenylphosphane (THF, 50 °C, 1 bar H 2 ). These investigations are supplemented by a demonstration of the κ 2 –κ 3 fluxionally of the triphos coordination in 1 by reversible reaction with [RuCl 2 ( p ‐cymene)] 2 at room temperature in CH 2 Cl 2 . The product of this reaction, the bimetallic complex [( p ‐cymene)Cl 2 Ru{(PPh 2 CH 2 )CMe(CH 2 PPh 2 ) 2 }Rh(COD)]PF 6 , was isolated and fully characterized, including determination of the solid‐state structure by X‐ray diffraction analysis. Despite this evidence for facile arm‐off dissociation of the triphos ligand in 1 , complex 2 , with or without triphenylphosphane, was found to be more efficient for the hydrogenation of styrene and cyclohexene. Notably, use of triphenylphosphane together with 2 was found to have beneficial effects – increasing the rate of styrene hydrogenation (in some cases) and helping to stabilise the metal center during cyclohexene hydrogenation. These observations are supported by mercury poisoning experiments and reactivity experiments with 2 in medium pressure sapphire NMR tubes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Type of Medium:
Online Resource
ISSN:
1434-1948
,
1099-0682
DOI:
10.1002/ejic.v2007:31
DOI:
10.1002/ejic.200700496
Language:
English
Publisher:
Wiley
Publication Date:
2007
detail.hit.zdb_id:
1475009-0
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