Migratory insertion reactions of indenyliridium dialkyls and alkyl and aryl hydrides

Foo, Thomas; Bergman, Robert G.

doi:10.1021/om00041a014

Cited by 37 publications

(13 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Analogous experimental features, e.g. linear dependence on alkyne concentration, negative entropy of activation, and lack of kinetic isotopic effect, were observed by Bergman and Foo for the insertion reaction of the iridium complex [IrH(Me)(η 5 -C 9 H 7 )(PMe 3 )] with tert -butylacetylene, and the data were interpreted according to the same kinetic analysis shown in Scheme 4 and eq 3 . Reaction rates of the iridium complex ( e.g.…”

Section: Discussionmentioning

confidence: 60%

“…In this respect, and in the context of this work, rhodium complexes [Rh(η 5 -C 9 H 7 )L 2 ] (L = ethylene, cyclooctene; L 2 = 1,5-cyclooctadiene) have been described as very efficient catalysts for the cyclotrimerization of alkynes to benzene derivatives in comparison with the isostructural cyclopentadienyl complexes . A kinetic and mechanistic investigation of the alkyne insertion reaction in the iridium complex [IrH(Me)(η 5 -C 9 H 7 )(PMe 3 )] has revealed the existence of a low barrier pathway for the coordination of the alkyne to the metal center …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η⁵-C₉H₇)(dppm)] (dppm = Bis(diphenylphosphino)methane)

Bassetti¹,

Casellato²,

Gamasa³

et al. 1997

Organometallics

View full text Add to dashboard Cite

The indenyl complexes [RuX(η 5 -C 9 H 7 )(dppm)] (dppm ) bis(diphenylphosphino)methane, X ) H, D) react with phenylacetylene to give the products of syn addition [Ru{(E)-CHdCXPh}(η 5 -C 9 H 7 )(dppm)] in toluene, in the temperature range 40-80 °C. The indenyl complexes [RuH(η 5 -C 9 H 7 )LL′] (L ) L′ ) PMe 2 Ph; L ) PPh 3 , L′ ) PMe 2 Ph; L ) PPh 3 , L′ ) PMe 3 ; LL′ ) dppe) and [RuH(η 5 -Me 3 C 9 H 4 )(CO)(PPh 3 )] and the cyclopentadienyl complex [RuH(η 5 -C 5 H 5 )(dppm)] do not react with PhCtCH, even under more forcing conditions. The complexes [RuH(η 5 -C 9 H 7 )LL′] (LL′ ) dppe; LL′ ) dppm; L ) L′ ) PMe 2 Ph; L ) PPh 3 , L′ ) PMe 3 ; L ) PPh 3 , L′ ) PMe 2 Ph) and the indenyl-substituted complexes [RuH(η 5 -Me 3 C 9 H 4 )(CO)(PR 3 )] (PR 3 ) PPh 3 , P i Pr 3 ) react with dimethyl acetylenedicarboxylate to give the alkenyl derivatives [Ru{(E)-C(CO 2 Me)dCH(CO 2 Me)}(η 5 -C 9 H 7 )LL′] and [Ru{(E)-C(CO 2 -Me)dCH(CO 2 Me)}(η 5 -Me 3 C 9 H 4 )(CO)(PR 3 )], respectively, in diethyl ether under reflux. The reaction of [RuH(η 5 -C 9 H 7 )LL′] with methyl propiolate yields the R-metalated alkenyl complexes [Ru{C(CO 2 Me)dCH 2 }(η 5 -C 9 H 7 )LL′] (LL′ ) dppe, dppm; L ) L′ ) PMe 2 Ph; L ) PPh 3 , L′ ) PMe 3 ) in refluxing diethyl ether. A kinetic study has been carried out for the reaction of the complexes [RuX(η 5 -C 9 H 7 )(dppm)] with phenylacetylene in toluene, by 1 H and 31 P{ 1 H} NMR spectroscopy. The reactions are first order with respect to the ruthenium complex and to the alkyne. The hydride and the deuteride complexes react at the same rate; intermediates are not detectable neither by kinetic studies nor by spectroscopy. The activation parameters, from rate measurements in the range 40-60 °C, are as follows: ∆H q ) 17 ( 2 kcal mol -1 , ∆S q ) -21 ( 4 cal mol -1 K -1 . An associative mechanism is proposed for the reaction, which involves the formation of an intermediate from the ruthenium complex and the alkyne under rate-determining steady-state conditions, followed by fast hydride migration and product formation. Due to the lack of reactivity of the analogous cyclopentadienyl complex [RuH(η 5 -C 5 H 5 )(dppm)], the reaction represents a case of indenyl effect. On the other hand, the indenyl and the cyclopentadienyl complexes react at comparable rates with the activated alkyne methyl propiolate.

show abstract

Section: Discussionmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η⁵-C₉H₇)(dppm)] (dppm = Bis(diphenylphosphino)methane)

Bassetti¹,

Casellato²,

Gamasa³

et al. 1997

Organometallics

View full text Add to dashboard Cite

show abstract

“…The organometallic chemistry of iridium(III) is dominated by compounds containing six-electron donor ligands such as cyclopentadienyl, indenyl, trispyrazolyl, or triphosphines and by complexes coordinating various monodentate phosphine ligands, generally two or more − However, despite this remarkable ability of substrate activation, the subsequent conversion of the activated substrates into functionalized organic products has been achieved in just a few cases, and the incorporation of such activation steps into catalytic cycles remains to be solved . This problem has been extensively discussed 2,4 and attributed to the inability of the products obtained in the activation step to generate new coordination vacancies, thus preventing further reaction with other substrates.…”

Section: Introductionmentioning

confidence: 99%

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

et al. 1999

View full text Add to dashboard Cite

The trisacetonitrile complexes [IrClH(PiPr3)(NCCH3)3]BF4 (1) and [IrH2(PiPr3)(NCCH3)3]BF4 (2) have been prepared in one-pot reactions with high yields by reaction of the iridium(I) dimers [Ir(μ-Cl)(coe)2]2 and [Ir(μ-OMe)(cod)2]2 with the phosphonium salt [HPiPr3]BF4. The rates of exchange between free acetonitrile and the labile acetonitrile ligands of complexes 1 and 2 have been measured by NMR spectroscopy. This kinetic study has shown that both complexes readily dissociate one acetonitrile ligand trans to hydride, giving rise to fluxional five-coordinate intermediates. Substitution products 3−7 have been obtained by treatment of complexes 1 and 2 with CO and PMe3. The structures determined for 3−7 can be rationalized on the basis of the steric requirements of the ligands, indicating that the products are formed by thermodynamic control. Ethene inserts reversibly into the Ir−H bond of 1 to give the compound [IrCl(Et)(PiPr3)(NCCH3)3]BF4 (8), which has been used for the preparation of the stable ethyliridium(III) complexes [IrCl(Et)(PiPr3)(Py)2(NCCH3)]BF4 (9) and [Ir(η2-O2CCH3)Cl(Et)(PiPr3)(NCCH3)3] (10), respectively. The molecular structure of 10 has been determined by X-ray crystallography. The reaction of 2 with ethene, at low temperature, results in the sequential formation of the ethene complex [IrH2(η2-C2H4)(PiPr3)(NCCH3)2]BF4 (11) and the diethyl derivative [Ir(Et)2(PiPr3)(NCCH3)3]BF4 (14). At room temperature in solution, 14 undergoes reductive elimination of ethane to form the iridium(I) species [Ir(PiPr3)(NCCH3)3]BF4 (15) and [Ir(PiPr3)(η2-C2H4)(NCCH3)2]BF4 (16). These cations readily react with H2 to regenerate 2, closing a cycle for ethene hydrogenation in which several participating species have been identified. The reaction of 2 with propene in solution also allows the characterization of products of propene coordination (17) and insertion (18). In this case, the species obtained after elimination of propane are products of allylic C−H activation: [IrH(η3-C3H5)(PiPr3)(NCCH3)2]BF4 (19) and [IrH(η3-C3H5)(η2-C3H6)(PiPr3)(NCCH3)]BF4 (20). The structure of complex 19 has been determined by X-ray diffraction, and the kinetics of dissociation of its two labile acetonitrile ligands have been studied by NMR spectroscopy. Complex 19 undergoes electrophilic activation of H2 to give propene and reform the starting complex 2.

show abstract

“…In the absence of C−H bond cleavage of the methyl group, other routes to C−C bond formation involving the reaction of 1 and alkynes are also available. Although less favorable than insertions involving metal hydrides, insertions of alkynes into metal−alkyl bonds have been observed . Particularly relevant to this study, the closely related species [Ir 2 H(CO) 3 (μ-CH 2 )(dppm) 2 ][CF 3 SO 3 ] and [RhIr(CH 3 )(CO) 3 (dppm) 2 ][CF 3 SO 3 ] were shown to yield the substituted-vinyl products [MIr(C(R)C(Me)R)(CO) 3 (dppm) 2 ][CF 3 SO 3 ] (M = Rh, Ir; R = CO 2 Me), through migratory insertion involving dimethyl acetylenedicarboxylate and the methyl ligand 7g…”

Section: Introductionmentioning

confidence: 99%

C−H Bond Activation and C−C Bond Formation in the Reactions of the Methyl Complex [Ir₂(CH₃)(CO)₂(Ph₂PCH₂PPh₂)₂][CF₃SO₃] with Alkynes

1999

View full text Add to dashboard Cite

The methyl complex [Ir 2 (CH 3 )(CO)(µ-CO)(dppm) 2 ][CF 3 SO 3 ] (1) reacts readily with a variety of alkyne molecules. With alkynes containing electron-withdrawing substituents (RCtCR′; R ) R′ ) CO 2 Me, CF 3 ; R ) CO 2 Me, R′ ) H), the alkyne-bridged products, [Ir 2 (CH 3 )(CO) 2 -(µ-alkyne)(dppm) 2 ][CF 3 SO 3 ], result. With other 1-alkynes (HCtCR, R ) Me, Ph) reaction at -80 °C results in oxidative addition to give acetylide hydrides [Ir 2 H(CH 3 )(CO) 2 (µ-C 2 R)-(dppm) 2 ][CF 3 SO 3 ], which upon warming undergo transfer of the hydride ligand to the β-carbon of the acetylide to give the vinylidene-bridged products. At ambient temperature methane elimination occurs, yielding the acetylide-bridged "A-frames", [Ir 2 (CO) Reaction of 1 with 1 equiv of acetylene proceeds through analogous acetylide and vinylidene intermediates; however under carbon monoxide exchange of a vinylidene hydrogen and the methyl ligand occurs to give a methylvinylidene-bridged hydride [Ir 2 (H)(CO) 3 (µ-CCHMe)(dppm) 2 ][CF 3 SO 3 ]. Reaction of 1 with an excess of acetylene results in the incorporation of two acetylene molecules, giving [Ir 2 (CH 3 , containing terminal methyl and acetylide ligands and bridging hydride and vinylidene groups. Reaction of 1 with a number of internal, nonactivated alkynes results first in the formation of the alkyne-bridged products, which slowly rearrange to the unusual species [Ir 2 H(CO) 2 (µ-CHCRC(H)R)(dppm) 2 ][CF 3 SO 3 ], in which cleavage of two C-H bonds of the methyl group has occurred accompanied by condensation of the resulting methyne group at one end of alkyne linkage and transfer of a hydrogen to the other end. The resulting hydrocarbyl moiety can be viewed as a vinylcarbene. The X-ray structures of three representative products are reported, including one of these vinylcarbenes (R ) C 2 H 5 ).

show abstract

Migratory insertion reactions of indenyliridium dialkyls and alkyl and aryl hydrides

Cited by 37 publications

References 2 publications

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η⁵-C₉H₇)(dppm)] (dppm = Bis(diphenylphosphino)methane)

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η⁵-C₉H₇)(dppm)] (dppm = Bis(diphenylphosphino)methane)

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

C−H Bond Activation and C−C Bond Formation in the Reactions of the Methyl Complex [Ir₂(CH₃)(CO)₂(Ph₂PCH₂PPh₂)₂][CF₃SO₃] with Alkynes

Contact Info

Product

Resources

About

Migratory insertion reactions of indenyliridium dialkyls and alkyl and aryl hydrides

Cited by 37 publications

References 2 publications

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η5-C9H7)(dppm)] (dppm = Bis(diphenylphosphino)methane)

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η5-C9H7)(dppm)] (dppm = Bis(diphenylphosphino)methane)

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

C−H Bond Activation and C−C Bond Formation in the Reactions of the Methyl Complex [Ir2(CH3)(CO)2(Ph2PCH2PPh2)2][CF3SO3] with Alkynes

Contact Info

Product

Resources

About

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η⁵-C₉H₇)(dppm)] (dppm = Bis(diphenylphosphino)methane)

Insertion Reactions of Alkynes into the Ru−H Bond of Indenylruthenium(II) Hydride Complexes. Mechanism of the Reaction of Phenylacetylene with [RuH(η⁵-C₉H₇)(dppm)] (dppm = Bis(diphenylphosphino)methane)

C−H Bond Activation and C−C Bond Formation in the Reactions of the Methyl Complex [Ir₂(CH₃)(CO)₂(Ph₂PCH₂PPh₂)₂][CF₃SO₃] with Alkynes