Highly Active Ruthenium Catalysts for Olefin Metathesis: The Synergy of N‐Heterocyclic Carbenes and Coordinatively Labile Ligands

Weskamp, Thomas; Kohl, Florian J.; Hieringer, Wolfgang; Gleich, Dieter; Herrmann, Wolfgang A.

doi:10.1002/(sici)1521-3773(19990816)38:16<2416::aid-anie2416>3.0.co;2-#

Cited by 464 publications

(175 citation statements)

References 6 publications

(14 reference statements)

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“…[7] They studied the reaction of [(R 3 P)ClPd(µ-Cl)] 2 with [(R 3 P)ClPt(µ-Cl)] 2 (R ϭ Pr, Bu) in chloroform by means of 31 P NMR. The two symmetrical complexes were shown to be in a dynamic equilibrium with the heterobimetallic compound [(R 3 P)ClPd(µ-Cl) 2 PtCl(PR 3 )]. In contrast to the above-mentioned rhodium complex, only a slight thermodynamic preference for the asymmetric complex was observed (K ϭ 5.3 for R ϭ Bu).…”

Section: Nmr Studiesmentioning

confidence: 99%

Asymmetric Halogeno-Bridged Complexes of the Late Transition Metals − A Computational and Experimental Study

Öhm

Schulz

Severin

2000

Eur. J. Inorg. Chem.

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Metathesis reactions of dinuclear halo‐bridged complexes of the late transition metals have been studied by NMR. For selected combinations of 15 different complexes, it has been shown that asymmetric complexes are formed in a dynamic equilibrium. The equilibrium constants have been calculated and the trends therein are discussed. A theoretical analysis of halo‐bridged complexes containing (C3H5)MX, (H3P)MX2, [(H3P)2MX]+, and (ppy)2RhCl fragments (M = Pd, Pt; X = Cl, Br, I; ppy = anion of 2‐phenylpyridine) has been carried out to gain further insight into (i) the influence of the bridging halogen atoms on the equilibrium, (ii) the electron transfer, (iii) the thermodynamic stability and the dynamic equilibrium behaviour, and (iv) structural differences between symmetric and asymmetric halo‐bridged complexes.

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Section: Nmr Studiesmentioning

confidence: 99%

Asymmetric Halogeno-Bridged Complexes of the Late Transition Metals − A Computational and Experimental Study

Öhm

Schulz

Severin

2000

Eur. J. Inorg. Chem.

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“…The well-defined Grubbs first (1 and 2) [1][2][3][4] and second (3) [5][6][7] generation precatalysts are found to be very active and robust toward a large number of substrates. These precatalysts however showed activity at room temperature in alkene metathesis reactions [2,8,9].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Application of Novel Ruthenium Catalysts for High Temperature Alkene Metathesis

et al. 2017

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Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ruthenium carbene complexes of the Grubbs second generation-type RuCl(H 2 IMes)(OˆN)(=CHPh), where,1-phenyl methanolato and 1-(2 -pyridinyl)-1-(2 -methoxyphenyl),1-phenyl methanolato, are synthesized in very good yields. At high temperatures, the precatalysts showed high stability, selectivity and activity in 1-octene metathesis compared to the Grubbs first and second generation precatalysts. The 2-/4-chloro-and 4-methoxy-substituted pyridinyl alcoholato ligand-containing ruthenium precatalysts showed high performance in the 1-octene metathesis reaction in the range 80-110 • C. The hemilabile 4-methoxy-substituted pyridinyl alcoholato ligand improved the catalyst stability, activity and selectivity for 1-octene metathesis significantly at 110 • C.

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“…Very recently N-heterocyclic carbenes [56] have been shown to have a phosphine-like ability to support catalysis by platinum group metals. Examples include carbene complexes used for C-C [57][58][59][60] and C-N [61,62] couplings and olefin metathesis [63][64][65][66]. They have the advantages of being readily synthesized and, if incorporated into chelating ligands, could readily be made modular, thus making them suitable for combinatorial/rapid screening work.…”

Section: Meoh + Co = Mecoohmentioning

confidence: 99%

Rapid screening and combinatorial methods in homogeneous organometallic catalysis

Loch

Crabtree

2001

Pure and Applied Chemistry

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Methods are discussed for rapid screening of soluble and polymer-bound homogeneous catalysts for activity. A polymer-bound phosphine library is synthesized, and a modular tridentate pincer CNC bis-carbene Pd complex is described. The possibility of C-bound His in metalloenzymes is raised.Homogeneous catalysis has much to offer Green Chemistry. By allowing reactions to occur at lower temperature and pressure, energy is saved. By enhancing selectivity, waste is avoided. Waste can even be essentially eliminated if catalysis allows atom-economic processes to be used. These are reactions like eq. 1 in which all the atoms of the reagents are incorporated into the product [1,2]. This particular rhodium-catalyzed reaction-the Monsanto Process-is a commercially important route to acetic acid [3]. In contrast, much conventional industrial chemistry still goes via reactions that produce stoichiometric amounts of inorganic salts or tainted water as byproducts. MeOH + CO = MeCOOH(1)For each new application, new homogeneous catalysts may well need to be identified and optimized, then understood mechanistically. Mechanization and computerization, now becoming more readily available and efficient, can help with all these goals. Combinatorial chemistry [4][5][6][7], together with rapid catalyst screening [8,9], has potential value in identification and optimization. The latest methods of computational and theoretical chemistry can give very valuable mechanistic information in ruling out otherwise plausible pathways and predicting structural information for transient species and transition states [10]. Here, we naturally discuss only the title topic, although by doing so we do not intend to detract from the importance of mechanistic understanding.The principles of combinatorial chemistry have been covered in several recent monographs and reviews [11][12][13][14][15][16]. In summary, the concept involves creating a large number of chemically distinct species-called a library-in a controlled way. This library is then assayed by a suitable rapid screening protocol to see if a desired response is elicited. The library members showing a good response, termed "hits", are then analyzed to determine the chemical structure responsible for the desired response.The field has its intellectual roots in an understanding of how the immune system works and in Merrifield's [17] approach to polypeptide synthesis. The immune system has the task of tagging foreign biomolecules to label them for attack. To do this, it creates a library of polypeptides of variable structure, then senses when one of these peptides by chance binds strongly to a foreign target, such as the surface of an invading bacterium, for example. The successful immune system peptide is then synthesized on a large scale to carry out its defense role in the body.

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Highly Active Ruthenium Catalysts for Olefin Metathesis: The Synergy of N‐Heterocyclic Carbenes and Coordinatively Labile Ligands

Cited by 464 publications

References 6 publications

Asymmetric Halogeno-Bridged Complexes of the Late Transition Metals − A Computational and Experimental Study

Asymmetric Halogeno-Bridged Complexes of the Late Transition Metals − A Computational and Experimental Study

Synthesis and Application of Novel Ruthenium Catalysts for High Temperature Alkene Metathesis

Rapid screening and combinatorial methods in homogeneous organometallic catalysis

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