Highly Active Pd(II) PCP-Type Catalysts for the Heck Reaction

Ohff, Manuela; Ohff, Andreas; Boom, and Milko E. van der; Milstein, David

doi:10.1021/ja9729692

Cited by 492 publications

(314 citation statements)

References 12 publications

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“…33 and N-heterocyclic carbenes (NHCs), 34 have led to significant breakthroughs in this area. From practical and economical considerations, however, the demand for phosphine-free heterogeneous systems is still extremely high in order to circumvent drawbacks imposed by homogeneous complexes.…”

Section: Hydroxyapatitementioning

confidence: 99%

Design of High-Performance Heterogeneous Metal Catalysts for Green and Sustainable Chemistry

Kaneda¹,

Ebitani²,

Mizugaki³

et al. 2006

Bulletin of the Chemical Society of Japan

143

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This account reviews a novel approach to designing high-performance heterogeneous metal catalysts using hydroxyapatites, montmorillonites, and hydrotalcites as macroligands of active metal species for aerobic alcohol oxidations, carbon-carbon bond formations, and one-pot syntheses. The catalytic systems using the above heterogeneous catalysts offer significant benefits in achieving environmentally friendly organic syntheses aiming towards Green and Sustainable Chemistry. Furthermore, the present preparation method for the immobilization of metal species is strikingly simple and allows a strong protocol for creating various nanostructured and functionalized heterogeneous catalysts.Green and Sustainable Chemistry (GSC) is a revolutionary philosophy that aims to bring about a sustainable society by improvement of the safety and environmental aspects of chemical processes and reduction of the risks of chemical products to people and the environment.1 The emphasis is on eliminating waste at the source-primary pollution prevention-rather than finding incremental end-of-pipe solutions. This concept aims to solve the societal problems of the last century associated with the mass production and consumption of materials, and plays a prime role in providing a venous function in society, encouraging reuse and circulation of resources.One of the powerful solutions in the move toward GSC is the replacement of traditional synthetic methods using harmful stoichiometric reagents that produce vast amounts of waste with cleaner and simple catalytic alternatives with high atom efficiency 1a and low E-factors. 1b Catalytic chemistry, therefore, is of ever-increasing importance because catalysis is a key element in material transformations at atomic and molecular levels, which are an essential realm of chemistry and chemical processes.Our approach to GSC is to develop a highly functionalized heterogeneous metal catalyst based on the unique characteristics of natural layered inorganic materials such as hydroxyapatite, montmorillonite, and hydrotalcite, by using them as macroligands for metal species.2 We consider the above inorganic materials to be advanced nano-scaled catalyst supports allowing for the control of the location of catalytically active metal species, which can be found, for example, on the surface, among the layers, or in the interlayer space. Furthermore, these materials are capable of creating catalytically active metal species responsible for targeted organic transformations involving monomers, chain-like species or giant clusters. The creation of well-defined active metal sites on a solid surface, as characterized by X-ray absorption spectroscopy, not only opens up an avenue to materials that boost catalytic performance, but also aids in the understanding of the molecular basis of heterogeneous catalysis. Another advantage of these catalysts is the possibility of a one-pot synthesis based on a cooperative action by several immobilized active species on the solid surface as multifunctional catalysts. The target react...

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Section: Hydroxyapatitementioning

confidence: 99%

Design of High-Performance Heterogeneous Metal Catalysts for Green and Sustainable Chemistry

Kaneda¹,

Ebitani²,

Mizugaki³

et al. 2006

Bulletin of the Chemical Society of Japan

143

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“…The iridium chemistry of this ligand has been reported previously [5]. There are also reports of palladium, platinum and rhodium chemistry [2,6,7], but there are no reports of dinuclear bridging compounds of this phosphine ligand. On the other hand, the corresponding phosphinite regularly form dinuclear complexes [6,8].…”

mentioning

confidence: 71%

“…hydridoiridium(III) which belongs to afamily of C(sp 3 )-Hactivated PCP complexes, showing interesting catalytic performance in C-Ccoupling reactions [1][2][3][4]. The crystal structure of the title compound shows how difficult it is to thermally displace cyclooctadiene ligands with phosphines.…”

Section: Bis[(di-tert-butylphosphino)methyl]cyclohexanechloro-mentioning

confidence: 99%

Crystal structure of μ-(cis-1,3-bis(di-tert-butylphosphinomethyl)- cyclohexane- k2-P,P)-bis[chloro(1,5-cyclooctadiene)iridium(I)] — tetrahydrofuran (1:0.5), Ir2Cl2(C8H12)2[C8H14P2(C4H9)4] · 0.5C4H8O

Arunachalampillai¹,

Olsson²,

Wendt³

2010

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of material )inathick-walled Schlenk flask. The flask was sealed, placed in an oil bath (200°C) and stirred for 2hresulting in adark brown solution. Heating this solution at 200°Cwith dihydrogen for 2hgave no change in the 31 PNMR spectrum. However, upon standing, as mall amount of light red crystals of X-ray quality preciptated and were shown to be the title compound. Experimental detailsThe Hatoms were positioned geometrically and treated as riding on their parent atoms with d(C-H) =0.93 -0.97 Å and U iso(H) = 1.2 U eq -1.5 U eq ,except for the tert-butyl hydrogens where this treatment gave unreasonable intermolecular H-H distances. The THF molecule is disordered around an inversion centre. DiscussionThe title compound appeared as aby-product in the synthesis of cis-1, 3-bis[(di-tert-butylphosphino) The crystal structure of the title compound shows how difficult it is to thermally displace cyclooctadiene ligands with phosphines. The iridium chemistry of this ligand has been reported previously [5]. There are also reports of palladium, platinum and rhodium chemistry [2,6,7], but there are no reports of dinuclear bridging compounds of this phosphine ligand. On the other hand, the corresponding phosphinite regularly form dinuclear complexes [6,8]. The iridium atoms exhibit apseudo-square-planar environment with the phosphine ligand bridging between the two iridium atoms and a cis-orientation of the chloride and phosphorus atoms.There are no significant intermolecular interactions, and the packing is mainly realized by dispersion forces. The intramolecular metal-metal distance is 8.65 Å and the shortest intermolecular distance is 7.16 Å.The crystal structure contains one disordered THF molecule per four iridium atoms.

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“…Current efforts focus on the use of organometallic pincersiloxane reagents for surface modification and on the use of pincer-metal silica hybrid materials for other catalytic conversions (e.g., C-C and C-X bond formation) [45,[64][65][66][67][68][69]. The integrity and stability of the silica support will be another important aspect of these studies.…”

Section: Resultsmentioning

confidence: 99%

Novel silica immobilized NCN-pincer palladium(II) and platinum(II) complexes: Application as Lewis acid catalysts

Mehendale

Bezemer²,

Walree³

et al. 2006

Journal of Molecular Catalysis A: Chemical

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Abstract2,6-Bis[(dimethylamino)methyl]phenyl (NCN-pincer) palladium(II) and platinum(II) complexes tethered to a trialkoxysilane coupling agent through a carbamate linkage were immobilized on various types of silica using a grafting or a sol-gel process. The resulting hybrid materials were characterized by IR spectroscopy (DRIFT) and solid state CP/MAS NMR ( 13 C and 29 Si). Based on these analyses, H-bond interactions between the carbamate carbonyl group of the complex and the free silanol groups on silica surface were established. The palladium-based materials were tested for their activity as Lewis acid catalysts in the aldol reaction between methyl isocyanoacetate and benzaldehyde. It was found that these materials can indeed be applied as catalysts in this reaction. Their repetitive reuse showed an inferior catalytic efficacy, which presumably was caused by a reconstitution of the silica support. These studies also revealed that simple silver-based salts are active catalysts in this aldol reaction.

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Highly Active Pd(II) PCP-Type Catalysts for the Heck Reaction

Abstract: The palladium-catalyzed vinylation of aryl halides, also known as the "Heck reaction" (eq 1) is a very useful synthetic

Cited by 492 publications

References 12 publications

Design of High-Performance Heterogeneous Metal Catalysts for Green and Sustainable Chemistry

Design of High-Performance Heterogeneous Metal Catalysts for Green and Sustainable Chemistry

Crystal structure of μ-(cis-1,3-bis(di-tert-butylphosphinomethyl)- cyclohexane- k2-P,P)-bis[chloro(1,5-cyclooctadiene)iridium(I)] — tetrahydrofuran (1:0.5), Ir2Cl2(C8H12)2[C8H14P2(C4H9)4] · 0.5C4H8O

Novel silica immobilized NCN-pincer palladium(II) and platinum(II) complexes: Application as Lewis acid catalysts

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