Carbon−Carbon Bond Formation between Adjacent Alkenyl Ligands:  η3-Allyl Iridium(III) and η4-Butadiene Iridium(I) Complexes from a cis-Bis(alkenyl) Iridium(III) Complex

Chin, Chong Shik; Lee, Hyungeui; Noh, Soyoung; Park, Hyeyun; Kim, Mieock

doi:10.1021/om030090r

Cited by 14 publications

(5 citation statements)

References 62 publications

(21 reference statements)

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“…In particular, thermally induced reactions of C−C reductive elimination have not been observed even under harsh experimental conditions. In this respect, the behavior of these bis-alkenyl and alkenyl-alkyl compounds is similar to that reported for the related bis-phosphine cation [Ir(CHCH 2 ) 2 (NCCH 3 ) 2 (PPh 3 ) 2 ] + , although is different from that of the monophosphine analogues [Ir(CHCHR) 2 (NCCH 3 ) 2 -(P i Pr 3 )] + , postulated as intermediates in the formation of Ir(I) butadiene complexes . However, complexes 7 − 11 have been found to readily react with a new equivalent of 2-vinylpyridine.…”

Section: Resultssupporting

confidence: 73%

C−H Activation and C−C Coupling Reactions in 2-Vinylpyridine Cationic Complexes of Iridium

et al. 2004

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The complex [IrH2(NCCH3)3(PiPr3)]BF4 (1) reacts with 2-vinylpyridine to form the hydride [IrH{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (3) in a reaction that likely involves the observed dihydride [IrH2(NC5H4-2-CHCH2-κ-N)(NCCH3)2(PiPr3)]BF4 (2). Crystallization of the C−H activation product 3 affords the dicationic derivative [IrH{μ-η2-NC5H4-2-(Z-CHCH)-κ-N,C}(NCCH3)(PiPr3)]2(BF4)2 (4). 3 reacts with 2-vinypyridine, CH2CH2, CH⋮CH, PhC⋮CH, tBuC⋮CH, and PhC⋮CPh to form the corresponding alkyl or alkenyl insertion products. The structure of [Ir(NC5H4-2-(Z-CHCH)-κ-N,C)(NC5H4-2-CH2CH2-κ-N,C)(NCCH3)(PiPr3)]BF4 (5), which contains two chelating ligands derived from 2-vinylpyridine, has been determined by X-ray diffraction. The other insertion products 7−11 retain the structure of the precursor 3 even after insertions of different regioselectivity, as evidenced by the 1-alkyne derivatives [Ir{C(Ph)CH2}{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (9) and [Ir(E-CHCHtBu){NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (10). All obtained insertion products are stable toward the reductive elimination of C−C bonds. However, derivatives 9 and 10 undergo a C−C coupling reaction to form [Ir{NC5H4-2-Z-(CHCH)-κ-N,C}{NC5H4-2-Z-(CHCH)CH(R)CH2-κ-N,C}(NCCH3)(PiPr3)]BF4 (R = Ph, 12; R = tBu, 13) after treatment with 2-vinylpyridine excess. These latter products are isostructural, despite the different stereochemistry of the alkenyl ligands in the precursors. Under similar conditions, both the alkyl complex [Ir(Et){NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)] BF4 (7) and the diphenylacetylene derivative [Ir{Z-C(Ph)CHPh}{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (11) form the compound [Ir{NC5H4-2-Z-(CHCH)-κ-N,C}2(NCCH3)(PiPr3)]BF4 (15), after elimination of ethane and cis-stilbene, respectively. These latter observations are discussed to conclude that the observed C−C coupling processes comprise the initial generation of an alkene at the coordination sphere of iridium followed by the alkene insertion into an Ir−C bond.

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Section: Resultssupporting

confidence: 73%

C−H Activation and C−C Coupling Reactions in 2-Vinylpyridine Cationic Complexes of Iridium

et al. 2004

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“…The dehydrocoupling of ethene at rhodium centers to form butadiene complexes has been previously observed and mechanisms based on initial oxidative coupling or C–H bond activation have been proposed. − Such processes are also related to alkene oligomerization reactions . Interestingly, the complex RhTp*(C 2 H 4 ) 2 [Tp* = tris(3,5-dimethyl-1-pyrazol-1-yl)hydroborate] undergoes dehydrocoupling to give a butadiene complex in solution (with the concomitant release of ethane), but in the solid state, a hydrido-allyl species is formed …”

Section: Resultsmentioning

confidence: 96%

Stoichiometric and Catalytic Solid–Gas Reactivity of Rhodium Bis-phosphine Complexes

et al. 2015

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The complexes [Rh( i Bu 2 PCH 2 CH 2 P i Bu 2 )L 2 ][BAr F 4 ] [L 2 = C 4 H 6 , (C 2 H 4 ) 2 , (CO) 2 , (NH 3 ) 2 ; Ar F = 3,5-C 6 H 3 (CF 3 ) 2 ] have been synthesized by solid−gas reactivity via ligand exchange reactions with, in some cases, crystallinity retained through single-crystal to single-crystal transformations. The solid-state structures of these complexes have been determined, but in only one case (L 2 = (NH 3 ) 2 ) is the cation ordered sufficiently to enable its structural metrics to be determined by single crystal X-ray diffraction. The onward solid-state reactivity of some of these complexes has been probed. The bisammonia complex [Rh( i Bu 2 PCH 2 CH 2 P i Bu 2 )(NH 3 ) 2 ][BAr F 4 ] undergoes H/D exchange at bound NH 3 when exposed to D 2 . The bis-ethene complex [Rh( i Bu 2 PCH 2 CH 2 P i Bu 2 )(C 2 H 4 ) 2 ][BAr F 4 ] undergoes a slow dehydrogenative coupling reaction to produce a material containing a 1:1 mixture of the butadiene complex and a postulated mono-ethene complex. The mechanisms of these processes have been probed by DFT calculations on the isolated Rh cations. All the solid materials were tested as heterogeneous catalysts for the hydrogenation of ethene. Complexes with weakly bound ligands (e.g., L 2 = (C 2 H 4 ) 2 ) are more active catalysts than those with stronger bound ligands (e.g., L = (CO) 2 ). Surface-passivated crystals, formed through partial reaction with CO, allow for active sites to be probed, either on the surface or the interior of the single crystal.

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“…Thus the protonation of cis ‐bis(ethenyl)iridium complex [Ir(―CHCH 2 ) 2 (CH 3 CN) 2 (PPh 3 ) 2 ] + ( 48 ) produces the η 3 ‐allyl complex [Ir(η 3 ‐CH 3 CHCHCH 2 )(NCCH 3 ) 2 (PPh 3 ) 2 ] 2+ ( 49 ) by the initial attack of proton on the β‐carbon of an ethenyl ligand, leading to C―C bond formation as suggested by the deuterium‐labeling experiments. Also η 4 ‐butadiene complexes Ir(η 4 ‐CH 2 CHCHCH 2 )(A)(PPh 3 ) 2 (A) ―CHCH― + NEt 3 ( 51 ), ―C≡CR ( 52 ) were prepared upon reaction of 48 with terminal alkynes (RC≡CH; R = Ph, and p ‐C 6 H 4 CH 3 ) in the presence of NEt 3 (Scheme ).…”

Section: Reactivitymentioning

confidence: 99%

Alkenyl complexes of platinum group metals: a platform for diverse reactivity patterns

Sravani

Venkatesh

Vijayakrishna

et al. 2014

Applied Organom Chemis

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Intermediates for many catalysis reactions reported in the literature are metal‐alkyl and metal‐alkenyl, including metallacycloalkane species. Synthesis and reactions of metal‐alkyl, alkenyl and metallacyle complexes have shown a great deal of development during the past few decades. This review summarizes the significant contributions reported on metal‐alkenyl compounds, specifically those containing at least a carbon chain with pendant alkene group [M―CH2CH2CHCH2]. Although metal‐alkenyl complexes are stable with strong chelating diphosphines and with a decrease in the ligand donor strength, the complexes can decompose without any ambiguity. For example, platinum‐dialkenyl complexes react readily via β‐hydrogen elimination and reductive elimination promoted by the nature of the ligand, solvent and length of carbon chains. These complexes can also undergo intramolecular irreversible isomerization and this leads to the selective catalytic isomerization of 1‐alkenes to 2‐alkenes in the presence of platinum‐dialkenyl complexes as catalysts. Perhaps the most striking manifestations of flexibility are the facile and complete intramolecular and intermolecular alkene metathesis to yield the corresponding metallacycloalkenes in the presence of Grubbs’ catalysts. The diverse chemical reactivity of these complexes demonstrates both the scope and complexity of metal‐alkenyl chemistry depending on the nature of ligand and metal. Copyright © 2014 John Wiley & Sons, Ltd.

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Carbon−Carbon Bond Formation between Adjacent Alkenyl Ligands: η³-Allyl Iridium(III) and η⁴-Butadiene Iridium(I) Complexes from a cis-Bis(alkenyl) Iridium(III) Complex

Cited by 14 publications

References 62 publications

C−H Activation and C−C Coupling Reactions in 2-Vinylpyridine Cationic Complexes of Iridium

C−H Activation and C−C Coupling Reactions in 2-Vinylpyridine Cationic Complexes of Iridium

Stoichiometric and Catalytic Solid–Gas Reactivity of Rhodium Bis-phosphine Complexes

Alkenyl complexes of platinum group metals: a platform for diverse reactivity patterns

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