Phosphine–olefin ligands: a facile dehydrogenative route to catalytically active rhodium complexes

Rhodium(I) catalyzed E/Z isomerization of dimethyl butenedioate

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19851274 ◽

1985 ◽

Vol 50 (6) ◽

pp. 1274-1282 ◽

Cited By ~ 4

Author(s):

Jaroslav Podlaha ◽

Miloš Procházka

Keyword(s):

Experimental Evidence ◽

Triphenylphosphine Oxide ◽

Active Species ◽

Equimolar Mixture ◽

Rhodium Complexes ◽

Hydride Complexes ◽

High Substrate ◽

First Order ◽

Highly Effective ◽

Catalytically Active

Hydride complexes of Rh(I) represent highly effective homogeneous catalysts of the isomerization of (Z)-dimethyl butenedioate (I) yielding (E)-dimethyl butenedioate (II) in benzene at 25 °C. The reaction catalyzed by RhH(P(C6H5)3)4 is first order both in I and in the catalyst, k = 0.51 l mol-1 s-1, Ea = 48 kJ mol-1, ΔS≠ = -46 J mol-1 K-1. At high substrate-to-catalyst ratios the catalyst is inactivated, which consists mainly in deoxygenation and decarbonylation of the E- and Z-esters with formation of methyl 2-butenoate, triphenylphosphine oxide, and carbonylocomplexes of Rh(I). Statistical redistribution of deuterium during the isomerization of equimolar mixture of I and [2,3-2H2]-I and other experimental evidence are consistent with the addition-elimination hydride mechanism of the isomerization involving σ-alkyl rhodium complexes as the intermediates and RhH(P(C6H5)3)2 as the catalytically active species.

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Phosphine—Olefin Ligands: A Facile Dehydrogenative Route to Catalytically Active Rhodium Complexes.

ChemInform ◽

10.1002/chin.200651030 ◽

2006 ◽

Vol 37 (51) ◽

Author(s):

Thomas M. Douglas ◽

Jerome Le Notre ◽

Simon K. Brayshaw ◽

Christopher G. Frost ◽

Andrew S. Weller

Keyword(s):

Rhodium Complexes ◽

Catalytically Active

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ChemInform Abstract: SELECTIVE PREPARATION OF CATALYTICALLY ACTIVE ZEOLITE-ENCAPSULATED RHODIUM COMPLEXES

Chemischer Informationsdienst ◽

10.1002/chin.198251335 ◽

1982 ◽

Vol 13 (51) ◽

Author(s):

T.-N. HUANG ◽

J. SCHWARTZ

Keyword(s):

Rhodium Complexes ◽

Catalytically Active

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Rh2Cl2(CO)4 adsorbed and tethered on gold powder: IR spectroscopic characterization and olefin hydrogenation activity

Canadian Journal of Chemistry ◽

10.1139/v00-190 ◽

2001 ◽

Vol 79 (5-6) ◽

pp. 578-586 ◽

Cited By ~ 5

Author(s):

Hanrong Gao ◽

Robert J Angelici

Keyword(s):

Spectroscopic Characterization ◽

Rhodium Complexes ◽

Olefin Hydrogenation ◽

Hydrogenation Catalysts ◽

Gold Powder ◽

Ir Studies ◽

Major Species ◽

Catalytically Active ◽

Unidentified Species ◽

Diffuse Reflectance Infrared

Catalysts were prepared by adsorbing Rh2Cl2(CO)4 directly on gold powder or on gold that contained the tethered ligands 2-(diphenylphosphino)ethane-1-thiol (DPET) or methyl 2-mercaptonicotinate (MMNT). Infrared (IR) studies (diffuse reflectance infrared Fourier transform (DRIFT)) of the catalyst RhAu prepared by adsorbing Rh2Cl2(CO)4 directly on Au indicate that a RhI(CO)2 species is present. IR studies of RhDPET-Au suggest that tethered cis-Rh(DPET)(CO)2Cl is the major species at relatively high Rh2Cl2(CO)4 loadings, but trans-Rh(DPET)2(CO)Cl is observable at low Rh2Cl2(CO)4 loadings. Spectral investigations of the catalyst RhMMNT-Au prepared by adsorbing Rh2Cl2(CO)4 on MMNT-Au suggest that tethered [cis-Rh(MMNT)2(CO)2]+Cl and (or) Rh(MMNT)(CO)2Cl are the major species at low Rh2Cl2(CO)4 loadings, while a new unidentified species predominates at high Rh2Cl2(CO)4 loadings. All three catalysts are active 1-hexene hydrogenation catalysts under the mild conditions of 40°C and 1 atm of H2; they are much more active than Au powder or Rh2Cl2(CO)4 in solution. Of the three catalysts, RhAu is the most active with a maximum turnover frequency (TOF) of 800 mol H2 per mol Rh per min while its turnover (TO) is 29 600 mol H2 per mol Rh during a 2-hour run. Under the conditions of 1-hexene hydrogenation, the catalysts lose their CO ligands. Thus, it appears that a form of Rh metal on Au is the catalytically active species.Key words: catalysis, olefin hydrogenation, gold powder, tethered rhodium complexes, infrared studies, adsorption, rhodium complexes.

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