Surface organometallic chemistry: reactivity of silica-bound rhodium allyl complexes and the genesis of highly dispersed supported rhodium catalysts

Foley, Henry C.; DeCanio, Stephen J.; Tau, Kwoliang D.; Chao, Kuo‐Hua; Onuferko, Julia H.; Dybowski, Cecil; Gates, B. C.

doi:10.1021/ja00348a021

Cited by 101 publications

(47 citation statements)

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“…4a shows the monochromatic XPS spectrum of the Rh 3d region of the RhC13 .xHzO reference sample. The Rh 3d doublet represents a single rhodium state with a Rh 3d5/2 binding energy of 310.0 eV, in good agreement with the values in the range of 309.7-310.3 eV reported in the literature [7,[10][11][12]. The C1 2p spectrum ( fig.…”

Section: The Rhc13"xh20 Catalyst Precursorsupporting

confidence: 87%

Preparation of a rhodium catalyst from rhodium trichloride on a flat, conducting alumina support studied with static secondary ion mass spectrometry and monochromatic X-ray photoelectron spectroscopy

1993

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Section: The Rhc13"xh20 Catalyst Precursorsupporting

confidence: 87%

Preparation of a rhodium catalyst from rhodium trichloride on a flat, conducting alumina support studied with static secondary ion mass spectrometry and monochromatic X-ray photoelectron spectroscopy

1993

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“…Different from the other substrates tested, styrene was hydrogenated by the homogeneous catalyst 1 at a rate significantly higher than that when the silica-grafted 2 was employed (TOF was 18.3 vs. 2.6 h −1 ) (Fig. 34,39,40 Different from styrene, 4-phenyl-1-butene was hydrogenated by the silica-grafted catalyst 2 at a rate higher than that when the soluble dihydride 1 was used (TOF was 3.8 h −1 vs. 1.1 h −1 ) (Fig. Again, 2 did not leach into the reaction solution, as indicated by the filtration test (dashed line in Fig.…”

Section: Styrene and 4-phenyl-1-butenementioning

confidence: 99%

Catalytic hydrogenation of liquid alkenes with a silica-grafted hydride pincer iridium(iii) complex: support for a heterogeneous mechanism

Rimoldi

Fodor

Bokhoven

et al. 2015

Catal. Sci. Technol.

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The previously reported silica-grafted iridiumĲIII) hydride complex ĳIrHĲO-SBA-15)ĲPOCOP)] (2), prepared by treating ĳIrH 2 ĲPOCOP)] (1) (POCOP is 1,3-bisĲ(di-tert-butylphosphino)oxy)benzene) with SBA-15 (mesoporous silica), hydrogenates liquid alkenes (1-decene, trans-5-decene, cyclohexene, styrene, and 4-phenyl-1-butene) at room temperature and under 1 atm H 2 . Internal alkenes react at a lower rate than the terminal ones. For the sake of comparison, the hydrogenation of the same substrates was studied with the homogeneous catalyst ĳIrH 2 ĲPOCOP)] (1). The heterogeneous catalyst 2 hydrogenates 1-decene, cyclohexene, and 4-phenyl-1-butene faster than 1, whereas the opposite is true for styrene and trans-5-decene, which suggests that different active species are involved in the heterogeneous and homogeneous reactions. Catalysis by a truly heterogeneous species is supported by a series of "hot filtration tests". NMR spectroscopic studies showed that 2 does not undergo degrafting upon longer exposure to alkenes compared to ethene under hydrogenation conditions.Catal. Sci. Technol. This journal is Scheme 1 Synthesis of 2 from ĳIrH 2 ĲPOCCOP)] (1). oxide surface, catalyses the hydrogenation of gaseous alkenes (ethene and propene) at a total pressure of 2 bar (absolute). 36 At room temperature, TOFs of 7.3 and 5.3 min −1 were achieved for ethene and propene, respectively, whereas the reaction at 70°C gave TOFs of 28.7 and 24.7 min −1 . Interestingly, the catalyst was active without any chemical or thermal activation, was recovered without any sign of decomposition after catalysis, and was reused without loss of activity.Some of us have recently reported that 2 and its soluble analogues ĳIrHĲiBu-POSS)ĲPOCOP)] (3) (iBu-POSS is isobutylsubstituted polysilsesquioxane, -OSi 8 O 12 iBu 7 ) and ĳIrH-ĲOSiMe 3 )ĲPOCOP)] (4) (Fig. 1) react with carbon monoxide to give the corresponding six-coordinated adducts, which then undergo reductive elimination of silanol and release the degrafted iridiumĲI) complex ĳIrĲCO)ĲPOCOP)]. 37 The reductive elimination of silanol is a major potential problem which the application of such grafted complexes in the hydrogenation of liquid olefins faces. The present work addresses the issue of degrafting during the catalytic hydrogenation of liquid alkenes, such as 1-and trans-5-decene, cyclohexene, styrene, and 4-phenyl-1-butene, which all underwent leaching tests. Furthermore, we report the stoichiometric reactions of 2 and its homogeneous analogues 3 and 4 with representative liquid alkenes, dihydrogen, as well as in the presence of an alkene-dihydrogen mixture.

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“…We continued to include an Rh À Rh contribution although the initial analysis gave no indication of such a contribution, because of the ease of reduction and potential for aggregation of rhodium in complexes on oxide supports. [9] The fits carried out in the most detail are summarized in Table 1. No fit with only two shells (contributions) was adequate.…”

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confidence: 99%

Molecular Heterogeneous Catalysis: A Single‐Site Zeolite‐Supported Rhodium Complex for Acetylene Cyclotrimerization

Kletnieks

Liang²,

Craciun

et al. 2007

Chemistry A European J

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By anchoring metal complexes to supports, researchers have attempted to combine the high activity and selectivity of molecular homogeneous catalysis with the ease of separation and lack of corrosion of heterogeneous catalysis. However, the intrinsic nonuniformity of supports has limited attempts to make supported catalysts truly uniform. We report the synthesis and performance of such a catalyst, made from [Rh(C(2)H(4))(2)(CH(3)COCHCOCH(3))] and a crystalline support, dealuminated Y zeolite, giving {Rh(C(2)H(4))(2)} groups anchored by bonds to two zeolite oxygen ions, with the structure determined by extended X-ray absorption fine structure (EXAFS) spectroscopy and the uniformity of the supported complex demonstrated by (13)C NMR spectroscopy. When the ethylene ligands are replaced by acetylene, catalytic cyclotrimerization to benzene ensues. Characterizing the working catalyst, we observed evidence of intermediates in the catalytic cycle by NMR spectroscopy. Calculations at the level of density functional theory confirmed the structure of the as-synthesized supported metal complex determined by EXAFS spectroscopy. With this structure as an anchor, we used the computational results to elucidate the catalytic cycle (including transition states), finding results in agreement with the NMR spectra.

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Surface organometallic chemistry: reactivity of silica-bound rhodium allyl complexes and the genesis of highly dispersed supported rhodium catalysts

Cited by 101 publications

References 0 publications

Preparation of a rhodium catalyst from rhodium trichloride on a flat, conducting alumina support studied with static secondary ion mass spectrometry and monochromatic X-ray photoelectron spectroscopy

Preparation of a rhodium catalyst from rhodium trichloride on a flat, conducting alumina support studied with static secondary ion mass spectrometry and monochromatic X-ray photoelectron spectroscopy

Catalytic hydrogenation of liquid alkenes with a silica-grafted hydride pincer iridium(iii) complex: support for a heterogeneous mechanism

Molecular Heterogeneous Catalysis: A Single‐Site Zeolite‐Supported Rhodium Complex for Acetylene Cyclotrimerization

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