Binuclear Complexes as Models for Adjacent-Metal Involvement in C−H Bond-Cleavage and C−C Bond-Formation Steps Relevant to Fischer−Tropsch Chemistry

Torkelson, Jeffrey R.; McDonald, Robert; Cowie, Martin

doi:10.1021/ja973927g

Cited by 37 publications

(24 citation statements)

References 7 publications

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“…Terminal alkynes are known to coordinate toward metal center to give stable π-alkyne or σ-alkynyl compound [6][7][8][9][10]. In fact, it has been well-documented that metal vinylidene is obtained directly from the rearrangement of π-coordinated terminal alkynes [6][7][8][9][10][11][12][13][14][15][16][17][18][19]39,40]. It seems reasonable to include the direct attack of H 2 O on the carbon of the Ir-(HC≡CR) to produce ketones and on the α-carbon of the vinylidene moiety (Ir=C=CHR) to yield a hydroxyl carbene compounds followed by reductive elimination to give aldehydes.…”

Section: Possible Pathways For the C-o Coupling From Alkyne Hydrationsmentioning

confidence: 99%

“…The dimerization of alkynes catalyzed by a variety of transition metal compounds has been extensively studied and suggested the elaborated mechanism [11][12][13][14][15][16][17][18]. The key step of alkyne coupling reaction has been commonly proposed to involve the rearrangement of metal π-alkyne to metal vinylidene form [11][12][13][14][15][16][17][18].…”

Section: Possible Pathways For the C-c Coupling From Alkyne Dimerizationmentioning

confidence: 99%

“…This resulting anionic radical compound could produce highly reactive species which will be used to catalyze the activation of organic substrates such as alkynes. Metal-catalyzed hydration and oligomerization of alkynes provide important processes in organic chemistry to aldehydes, ketones, and conjugated olefin compounds since they are the carbon-oxygen [6][7][8][9][10] and -carbon [11][12][13][14][15][16][17][18][19] bond forming reactions which produce a variety of new inexpensive starting materials.…”

Section: Introductionmentioning

confidence: 99%

“…Among water-soluble ligands, PAr 3 (P(m-C 6 H 4 SO 3 Na) 3 ) is the most commonly used ligand to prepare water-soluble metal compounds [27][28][29][30][31][32]. Iridium-Cp * (C 5 Me 5 -) compounds have been investigated and have drawn much attention due to their diverse and interesting reactivity with alkynes [11][12][13][14][15][16][17][18][27][28][29][30][31][32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

“…Since it is well-known that terminal alkynes can be activated by organoiridium compounds [11][12][13][14][15][16][17][18], this voltammetric observation prompted us to look into details of reduced-metal catalyzed activation of alkynes in biphasic (H 2 O/CH 2 ClCH 2 Cl) solution. The biphasic…”

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confidence: 99%

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C-C and C-O Coupling Reactions of Terminal Alkynes by a Water Soluble Organoiridium Electron-transfer Mediator in Thin Layer of Water on Gold Electrode

Chong¹,

Dick²,

Shin³

2012

Organic Chem Curr Res

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2+ was previously reported [38].Since it is well-known that terminal alkynes can be activated by organoiridium compounds [11][12][13][14][15][16][17][18], this voltammetric observation prompted us to look into details of reduced-metal catalyzed activation of alkynes in biphasic (H 2 O/CH 2 ClCH 2 Cl) solution. The biphasic AbstractAn electrochemical reduction process is described for the rapid and efficient conversion of terminal alkynes into useful products. Terminal alkynes (HC≡CR; R = C 6 H 5 , p-C 6 H 4 CH 3 , CH 2 C 6 H 5 , C 6 H 9 ) were hydrated and dimerized by cathodic reduction of catalytic amount (5 %) of [Cp * Ir(NCMe) 2 (PAr 3 )](OTf) 2 , 1, (E pc = −620 mV vs Ag/AgCl) through an aqueous/nonaqueous interface. Thin aqueous layer containing water-soluble compound 1 was formed on gold electrode. The cathodic reduction current height of 1 increases as increasing the concentration of terminal alkynes. The electrolysis of 1 while contacting with terminal alkynes containing organic solvent produced ketones, aldehydes and dimerized enyne products from terminal alkyne/water reaction systems. A new micro-scale electrocatalysis technique is depicted.

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Section: Possible Pathways For the C-o Coupling From Alkyne Hydrationsmentioning

confidence: 99%

Section: Possible Pathways For the C-c Coupling From Alkyne Dimerizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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C-C and C-O Coupling Reactions of Terminal Alkynes by a Water Soluble Organoiridium Electron-transfer Mediator in Thin Layer of Water on Gold Electrode

Chong¹,

Dick²,

Shin³

2012

Organic Chem Curr Res

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Alkene C−H Activations at Dinuclear Complexes Promoted by Oxidation

et al. 2002

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Several recent discoveries in the chemistry of transition metal di-and polynuclear complexes have disclosed new methods of hydrocarbon activation and functionalization, favored by polynuclear environments. [1,2] In parallel, considerable progress has been made in understanding the reactivity features resulting from multimetallic reaction sites. [1, 3,4] Together, such advances may contribute to the rational design of new catalysts and applications based on this type of compound. However, the proximity of the metal centers is likely to have significant repercussions for the reactivity, which remain to be determined.In our recent studies on ™open-book∫ d 8 diiridium complexes with N-donor bridges, we have observed a remarkable substrate selectivity in the reactions of these compounds towards oxidative addition reactants. Whereas the d 8 diiridium complexes underwent fast S N 2 oxidative additions with substrates such as halocarbons, [4] the additions of less-polar reactants such as dihydrogen were not observed. The oxidation of these d 8 d 8 diiridium compounds, to species of d 6 d 8 or d 7 d 7 electronic configurations, gave dihydrogen-activating compounds. [5] Here we report that such an oxidation strategy also allows the transformation of nonreactive d 8 d 8 compounds into dinuclear CÀH activating species.The treatment of the diamidonaphthalene ((NH 2 )naphth)bridged diiridium (iii) complex [Ir 2 (m-1,8-(NH) 2 naphth)-(m-H)H 3 (NCCH 3 )(PiPr 3 ) 2 ] (1) with two equivalents of an internal alkyne such as 2-butyne or diphenylacetylene afforded diiridium(i) derivatives of the formula [Ir 2 (m-1,8-(NH) 2 naphth)(h 2 -Z-RHCCHR) 2 (PiPr 3 ) 2 ] (R Me (2), Ph (3)) [Eq. (1)]. The solution NMR spectra of both compounds indicate symmetric C 2 structures with a transoid arrangement of nonrotating Z-alkene ligands. These features have been confirmed by the X-ray crystallographic determination of the structure of 2, [6] (Figure 1). reaction see: M. AlajarÌn, C. Conesa, H. S. Rzepa, J. Chem. Soc.

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