Mimicking the HDS activity of ruthenium-based catalysts 2:: The hydrogenation of benzo[b]thiophene to 2,3-dihydrobenzo [b]thiophene

被引:49
作者
Bianchini, C
Meli, A
Moneti, S
Oberhauser, W
Vizza, F
Herrera, V
Fuentes, A
Sánchez-Delgado, RA
机构
[1] CNR, Ist Studio Stereochim & Energet Composti Coor, I-50132 Florence, Italy
[2] Inst Venezolano Invest Cient, Caracas 1020A, Venezuela
关键词
D O I
10.1021/ja983224e
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The ruthenium(II) tris-acetonitrile complex [(triphos)Ru(MeCN)(3)]BPh(4) (1) is an extremely efficient catalyst precursor for the regioselective hydrogenation of benzo[b]thiophene (BT) to 2,3-dihydrobenzo[b]thiophene (DHBT) in homogeneous phase under mild reaction conditions (THF, 40-100 degrees C, 1-30 bar H(2)) [triphos = MeC(CH(2)PPh(2))(3)]. At 30 bar of H(2) and 100 degrees C, BT is converted to DHBT with an average rate of 500 mol of product (mol of cat)(-1) h(-1). During the catalytic reactions with PH(2) > 5 bar, the acetonitrile ligands in 1 are transformed into a mixture of NHEt(2), NEt(3), and NH(3), while the termination ruthenium products are the monohydrido complexes [(triphos)Ru(H)(NH(3))(2)]BPh(4), [(triphos)Ru(H)(NH(3))(NH(2)Et)]BPh(4), and [(triphos)Ru(H)(NH(3))(eta(1)-SDHBT)]BP(4). Below 5 bar of Hz, no hydrogenation of MeCN occurs and all of the ruthenium is recovered as [(triphos)Ru(H)(NCMe)(eta(1)-S-DHBT)]BPh(4) All of these Ru(II) hydride complexes catalyze the hydrogenation of BT to DHBT as efficiently as 1. The substitution of D(2) for H2 in a catalytic reaction shows that BT is selectively cis-deuterated to DHBT-d(2) with no deuterium enrichment in either the unreacted BT or the arene ring of DHBT. Water in the reaction mixture decreases the hydrogenation rate of BT due to the formation of the mu-OH and acetate Ru(II) complexes [(triphos)Ru(mu-OH)(3)Ru(triphos)]BPh(4) and [(triphos)Ru(O(2)CCH(3))(OH(2))]BPh(4), which are catalytically inactive. The acetate complex is suggested to form via hydration of a MeCN ligand in the catalyst precursor. Catalytic runs at 30 and 2 bar of H were studied in situ by high-pressure NMR spectroscopy. The kinetics of the hydrogenation of BT in the presence of 1 were studied by gas adsorption techniques at different catalyst, substrate, and dihydrogen concentrations and at different temperatures. The kinetic data together with all of the other evidence accumulated allowed us to deduce a catalytic cycle in which the reversible dissociation of the thioether product from the metal center in the catalyst [(triphos)RuH](+) is a rate-limiting step. A comparison of the hydrogenation reactions of BT catalyzed by either the Ru(II) 14e(-) fragment [(triphos)RuH](+) or the Ru(0) 16e(-) fragment [(triphos)RuH](-) has provided some clues to unravel a number of mechanistic aspects of the HDS of thiophenes over single-component catalysts. In particular, the occurrence of either hydrogenation to thioether or hydrogenolysis to thiol has been related with the metal basicity.
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页码:7071 / 7080
页数:10
相关论文
共 87 条
  • [1] MOLYBDENUM IN HYDRODESULFURIZATION CATALYSTS
    AMBERG, CH
    [J]. JOURNAL OF THE LESS-COMMON METALS, 1974, 36 (1-2): : 339 - 352
  • [2] ANGELICI RJ, 1995, B SOC CHIM BELG, V104, P265
  • [3] STRUCTURAL ASPECTS OF THIOPHENE COORDINATION IN TRANSITION-METAL COMPLEXES
    ANGELICI, RJ
    [J]. COORDINATION CHEMISTRY REVIEWS, 1990, 105 : 61 - 76
  • [4] HETEROGENEOUS CATALYSIS OF THE HYDRODESULFURIZATION OF THIOPHENES IN PETROLEUM - AN ORGANOMETALLIC PERSPECTIVE OF THE MECHANISM
    ANGELICI, RJ
    [J]. ACCOUNTS OF CHEMICAL RESEARCH, 1988, 21 (11) : 387 - 394
  • [5] [Anonymous], ENCY INORGANIC CHEM
  • [6] ARCE AJ, 1994, ANGEW CHEM INT EDIT, V33, P1381, DOI 10.1002/anie.199413811
  • [7] ASHWORTH TV, 1971, J CHEM SOC CHEM COMM, P936
  • [8] HOMOGENEOUS CATALYTIC-HYDROGENATION .6. SYNTHETIC AND MECHANISTIC ASPECTS OF THE REGIOSELECTIVE REDUCTIONS OF MODEL COAL NITROGEN, SULFUR, AND OXYGEN HETEROAROMATIC-COMPOUNDS USING THE (ETA-5-PENTAMETHYLCYCLOPENTADIENYL)RHODIUM TRIS(ACETONITRILE) DICATION COMPLEX AS THE CATALYST PRECURSOR
    BARALT, E
    SMITH, SJ
    HURWITZ, J
    HORVATH, IT
    FISH, RH
    [J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1992, 114 (13) : 5187 - 5196
  • [9] C-S bond cleavage of benzo[b]thiophene at ruthenium
    Bianchini, C
    Masi, D
    Meli, A
    Peruzzini, M
    Vizza, F
    Zanobini, F
    [J]. ORGANOMETALLICS, 1998, 17 (12) : 2495 - 2502
  • [10] Mimicking the HDS activity of ruthenium-based catalysts. Homogeneous hydrogenolysis of benzo[b]thiophene
    Bianchini, C
    Meli, A
    Moneti, S
    Vizza, F
    [J]. ORGANOMETALLICS, 1998, 17 (12) : 2636 - 2645