Browsing by Author "Leus, Karen"

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    Alkyl Group-Tagged Ruthenium Indenylidene Complexes: Synthesis, Characterization and Metathesis Activity
    (Elsevier, 2015) Yu, Baoyi; Hamad, Fatma B.; Leus, Karen; Lyapkov, Alex A.; Van Hecke, Kristof; Verpoort, Francis
    We report on the synthesis of ruthenium indenylidene catalysts [RuCl2(3-R-1-indenylidene)(PCy3)2inwhich R is iso-propyl (7a), tert-butyl (7b) or cyclohexyl (7c)]. The obtained alkyl tagged indenylidenecatalysts were analyzed by means of IR, elementa l analysis, NMR and single crystal X-Ray diffractionanalysis. Furthermore, the catalytic performance of these new complexes was examined in dif ferentmetathesis reactions: ring-closing metathesis (RCM), ring-closing ene-yne metathesis (RCEYM), ring-opening metathesis polymerization (ROMP) and cross metathesis (CM), exhibiting a comparable activ-ity in comparison with the commercially available catalyst 3a
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    Effect of the Bulkiness of Indenylidene Moieties on the Catalytic Initiation and Efficiency of Second-Generation Ruthenium-Based Olefin Metathesis Catalysts
    (2016) Yu, Baoyi; Luo, Zhixiong; Hamad, Fatma B.; Leus, Karen; Van Hecke, Kristof; Verpoort, Francis
    We report on the synthesis and characterization of the second generation of ruthenium catalysts bearing various sized indenylidene ligands, denoted as RuCl2(3-(2,6-xylyl)-1-indenylidene)(SIMes)(PCy3) 5a, RuCl2(4-methyl-3-(o-tolyl)-1- indenylidene)(SIMes)(PCy3) 5b, RuCl2(3-1-naphthyl-1-indenylidene)(SIMes)(PCy3) 5c and RuCl2(3-(p-fluorophenyl)-1- indenylidene)(SIMes)(PCy3) 5d. The obtained complexes were characterized by NMR, IR, HRMS and elemental analysis. Moreover, the configurations of complexes 5a, 5b and 5d were confirmed by single-crystal X-ray diffraction analysis. The catalytic performance of the obtained complexes 5a-d were evaluated in several olefin metathesis reactions: the RCM of substrates 6 and 7, the RCEYM of substrate 8 and the ROMP of COD in comparison with the commercially available catalyst 3a. Careful analysis of the catalysts performance and single-crystal X-ray diffraction data of the obtained complexes reveals that the steric modification on the 3-phenyl group can have an obvious influence on the ligands congestion around the ruthenium center and hence, alters the catalytic activities in metathesis reactions. Additionally, the better performing complex 5a was further investigated in the RCM of substrate 6 in comparison with complex 3c and bench mark complexes 1b, 2 and 3a.
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    Synthesis and Characterization of Non-Chelating Ruthenium–Indenylidene Olefin Metathesis Catalysts Derived From Substituted 1,1-Diphenyl-2-Propyn-1-Ols
    (2015) Yeates, Baoyi; Xie, Yu; Hamad, Fatma B.; Leus, Karen; Lyapkov, Alex A.; Van Hecke, Kristof; Verpoort, Francis
    We report on the synthesis and characterization of the first generation of modified non-chelating indenylidene ruthenium catalysts denoted as RuCl2(4-methyl-3-(o-tolyl)-1-indenylidene)(PCy3)2 5a, RuCl2(3-(p-fluorophenyl)-1-indenylidene)(PCy3)2 5b, RuCl2(3-(2,6-xylyl)-1-indenylidene)(PCy3)2 5c and RuCl2(3-(1-naphthyl)-1-indenylidene)(PCy3)2 5d. The obtained complexes of 5a–d were characterized by means of NMR spectroscopy and elemental analysis. Moreover the structures of 5a–d were confirmed by single-crystal X-ray diffraction and compared with the standard ruthenium indenylidene complex 3 and the chelating benzylidene complex 2. Additionally, the catalytic performances of the obtained complexes 5a–d were evaluated in various metathesis reactions demonstrating that the ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) reactions revealed a similar catalytic activity in comparison with the reference indenylidene catalyst 3.