Reactivity differences between molecular and surface silanols in the preparation of homogeneous and heterogeneous olefin metathesis catalysts

Blanc, Frédéric; Chabanas, Mathieu; Copéret, Christophe; Fenêt, Bernard; Herdweck, Eberhardt

doi:10.1016/j.jorganchem.2005.04.028

Cited by 51 publications

(37 citation statements)

References 59 publications

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“…[101,106] Access to well-defined imido Mo alkylidene complexes was also realized by reaction of the nitrido ligand in [Mo( N)A C H T U N G T R E N N U N G (CH 2 -t-Bu) 3 ] with the surface silanol of silica (Scheme 19). [107,108] The trisalkyl intermediate cannot be isolated and gives directly 23 www.asc.wiley-vch.de nols gives very stable trisalkylimidosiloxy complexes, which need to be heated at > 80 8C to loose 2,2-dimethylpropane to provide a highly unstable olefin metathesis catalyst. [108] Moreover, note that protonation of the nitrido ligand is not observed upon reaction of [Mo( N)A C H T U N G T R E N N U N G (O-t-Bu) 3 ] with surface siloxy ligands.…”

Section: Grafting Hydrocarbyl Complexesmentioning

confidence: 99%

Strategies to Immobilize Well‐Defined Olefin Metathesis Catalysts: Supported Homogeneous Catalysis vs. Surface Organometallic Chemistry

Copéret,

Basset

2007

Adv Synth Catal

210

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This review is mainly devoted to a description of the strategies that have been implemented to develop well-defined olefin metathesis catalysts immobilized on solid supports. Two main approaches have been investigated involving supported homogenous catalysts or heterogeneous catalysts prepared by surface organometallic chemistry. Advantages, limitations and possible developments of these systems are discussed.

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Section: Grafting Hydrocarbyl Complexesmentioning

confidence: 99%

Strategies to Immobilize Well‐Defined Olefin Metathesis Catalysts: Supported Homogeneous Catalysis vs. Surface Organometallic Chemistry

Copéret,

Basset

2007

Adv Synth Catal

210

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“…[20] Here, we show that it is in fact a welldefined alkylidyne complex, and the necessary propagating alkylidene ligand [21] is probably generated in the presence of olefins as already proposed for other oxide supported group 6 alkylidyne complexes. [17,18,22,23] The preparation of the corresponding hydride was Figure S2), which are regenerated (95 %) upon treatment with H 2 at 80 8C. Therefore, these bands can be assigned to n (WÀH) vibrations.…”

mentioning

confidence: 98%

Silica‐Alumina‐Supported, Tungsten‐Based Heterogeneous Alkane Metathesis Catalyst: Is it Closer to a Silica‐ or an Alumina‐Supported System?

et al. 2007

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Grafting of [W(C‐t‐Bu)(CH2‐t‐Bu)3] (1) on silica‐alumina partially dehydroxylated at 500 °C generates a surface complex [(SiO)W(C‐t‐Bu)(CH2‐t‐Bu)3] (2) as evidenced by mass balance analysis, IR, and NMR spectroscopy. Upon treatment of this species under H2, a tungsten hydride derivative, [(SiO)(EO)W(H)x] (3), (E=Si or Al), is formed. Both of these complexes are active as alkane metathesis catalysts. The activity of this hydride is similar to that observed for the tungsten hydride‐supported on alumina and much greater than that obtained on silica. Noteworthy are the selectivities in higher alkane homologues, that is Cn+1>Cn+2, which are fully consistent with olefin metathesis being the key homologation process.

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“…For this purposes, the reaction of a polymer-bound silver perfluoroalkanesulfonate with the terminal bromo or, respectively, chloro group appeared suitable. The principal applicability of this reaction was (15). Selected bond distances (pm) and angles (8): Mo(1)ÀN (2) 172 (2), Mo (1)ÀN (1) 175 (2), Mo(1)ÀC (11) 203 (3), Mo (1)ÀC (1) demonstrated by reacting 1-bromooctane with silver trifluoromethanesulfonate in tetrahydrofuran.…”

Section: Immobilization Of Catalystsmentioning

confidence: 99%

“…Mo{N[2,6-Me 2 -4(6-BrC 6 H 12 )]C 6 H 2 } 2 (CH 2 CMe 2 C 6 H 5 ) 2 (15) Compound 11 (0.50 g, 0.61 mmol) was dissolved in 50 mL of diethyl ether. The solution was cooled to À40 8C and 2 equivs.…”

Section: Mo{na C H T U N G T R E N N U N G [26-a C H T U N G T R E Nmentioning

confidence: 99%

“…[13,14] Alternatively, a silica-immobilized mimic of the Schrock catalyst, ( SiO)MoA C H T U N G T R E N N U N G (=NH)A C H T U N G T R E N N U N G (= CH-t-Bu)A C H T U N G T R E N N U N G (CH 2 -t-Bu), was recently reported. [15] Quite recently, CopØret, Basset, Emsley and Schrock reported in a joint paper on the immobilization of MoA C H T U N G T R E N N U N G [=N-2,6-A C H T U N G T R E N N U N G (2-Pr) 2 …”

Section: Introductionmentioning

confidence: 99%

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Polymer‐Supported Chiral Schrock Catalysts Immobilized via the Arylimido Ligand

et al. 2006

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The immobilization of both chiral and non-chiral versions of the Schrock catalyst via the arylimido ligand was accomplished for the first time. For this purpose, four different 4-(6-halogenohexyl)-2,6-R 2 -anilines, i.e., {4-[6-X-(CH 2 ) 6 ]-2,6-R 2 -C 6 H 2 -NH 2 } (7: R= Me, X = Br; 8: R= Me, X = Cl, 9: R= 2-Pr, X = Cl, 10: R= 2-Pr, X = Br) were prepared and used for the synthesis of the corresponding MobisA C H T U N G T R E N N U N G (imido)dichloro complexes Mo{N-2,6-R 2 -4-[6-X-(CH 2 ) 6 ]-C 6 H 2 } 2 Cl 2 ·DME (11: R= Me, X = Br; 12: R = Me, X = Cl; 13: R= 2-Pr, X = Cl; 14: R= 2-Pr, X = Br). Compounds 11-14 were transformed into the corresponding Mo-bisA C H T U N G T R E N N U N G (imido)dialkyl complexes Mo{N-2,6-R 2 -4-[6-X-(CH 2 ) 6 ]-C 6 H 2 } 2 (CH 2 CMe 2 Ph) 2 (15: R= Me, X = Br; 16: R= Me, X = Cl, 17: R= 2-Pr, X = Cl; 18: R= 2-Pr, X = Br). These were used for the synthesis of the Mo-imidoalkylidene triflates·DME (19: R= Me, X = Br; 20: R= 2-Pr, X = Br, 21: R= 2-Pr, X = Cl). Compounds 19--21 were used in the synthesis of the Schrock type catalysts H T U N G T R E N N U N G (CHCMe 2 Ph)[OC-A C H T U N G T R E N N U N G (CH 3 )A C H T U N G T R E N N U N G (CF 3 ) 2 ] (23), Mo{N-2,6-Me 2 -4-[6-Br-(CH 2 ) 6 ]-C 6 H 2 }A C H T U N G T R E N N U N G (CHCMe 2 Ph)[(R)-BIPHEN] (24) and MoA C H T U N G T R E N N U N G {N-2,6-A C H T U N G T R E N N U N G (2-Pr) 2 -4-[6-Br-(CH 2 ) 6 ]-C 6 H 2 }A C H T U N G T R E N N U N G (CHCMe 2 Ph)[(R)-BIPHEN] (25). Compounds 22, 24and 25 were immobilized on Ag-perfluoroalkylsulfonate-modified PS-and PS-DVB materials to yield the corresponding immobilized catalysts Mo{N-2,6-Me 2 -4-28). These were used in a series of ring-closing metathesis (RCM), ringopening cross metathesis, asymmetric RCM and desymmetrization reactions. The use of 27 and 28 resulted in values for enantiomeric excess (ee) virtually identical to those obtained with the corresponding homogeneous chiral catalysts.

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Reactivity differences between molecular and surface silanols in the preparation of homogeneous and heterogeneous olefin metathesis catalysts

Cited by 51 publications

References 59 publications

Strategies to Immobilize Well‐Defined Olefin Metathesis Catalysts: Supported Homogeneous Catalysis vs. Surface Organometallic Chemistry

Strategies to Immobilize Well‐Defined Olefin Metathesis Catalysts: Supported Homogeneous Catalysis vs. Surface Organometallic Chemistry

Silica‐Alumina‐Supported, Tungsten‐Based Heterogeneous Alkane Metathesis Catalyst: Is it Closer to a Silica‐ or an Alumina‐Supported System?

Polymer‐Supported Chiral Schrock Catalysts Immobilized via the Arylimido Ligand

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