Coordinated carbenes from electron-rich olefins on RuHCl(PPr3i)2

Coalter, Joseph N.; Bollinger, John C.; Huffman, John C.; Werner‐Zwanziger, Ulrike; Caulton, Kenneth G.; Davidson, Ernest R.; Gérard, Hélène; Clot, Eric; Eisenstein, Odile

doi:10.1039/a907624g

Cited by 87 publications

(102 citation statements)

References 20 publications

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“…[11] Access to structure D (that would precede b-hydride elimination [11,12] to generate the hydride alkene isomer 2 b) requires, assuming chiral integrity of the alkyl carbon, metal inversion through a five-coordinate structure such as C. This is expected to be energetically costly, [13] and accordingly, the 1-2 a isomerization requires prolonged heating at temperatures around 100 8C. The equilibrium constant shows little temperature dependence (K eq % 8 in C 6 D 12 , temperature range 90-130 8C) and favors the hydride alkylidene 1.…”

Section: The Thermal Reaction Of Tpmentioning

confidence: 99%

A Measureable Equilibrium between Iridium Hydride Alkylidene and Iridium Hydride Alkene Isomers

et al. 2004

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Dedicated to Professor H. Werner on his 70th birthdayRearrangement between isomeric M-olefin and M-alkylidene units (in which M is a transition-metal atom) is a fundamental transformation key to many homogeneous and heterogeneous catalytic processes.[1] However, whereas conversion of a metal alkylidene into the corresponding metal alkene has been known for some time, particularly for cationic electrophilic metal alkylidenes, [2,3] the reverse transformation is a rarely observed process, known only for a few transition-metal complexes that have few d electrons.[4] Moreover, detection of a thermoneutral (or almost thermoneutral) redistribution of this kind, that is, a process whereby the alkene and the alkylidene isomers exist in equilibrium, finds little precedent and appears to be limited to some complexes of the early transition metals.[5] We report herein that a d 6 Tp Me 2 Ir III fragment allows attainment of an equilibrium mixture of the hydride alkylidene and hydride alkene structures 1 and 2 a (Scheme 1), through a reaction that implies the activation of sp 3 CÀH bonds of o-C 6 H 4 (OH)CH 2 CH 3 . The thermal reaction of TpMe 2 Ir(C 6 H 5 ) 2 (N 2 ) [6a] and 2-ethylphenol (ca. 1:2.5 molar ratio, cyclohexane solvent, 60 8C) produces the hydride alkylidene 1 (Scheme 1) as the main product (95 % conversion into products as determined by NMR spectroscopy; 90 % yield of isolated 1). Presumably, the reaction starts with alcoholysis of one of the IrÀC 6 H 5 bonds (structure A, Scheme 1), and this is then followed by a facile, double activation [6,7] of the methylenic CÀH bonds of the ortho ethyl substituent. The CÀH bond cleavage is highly regioselective. Monitoring by 1 H NMR spectroscopy reveals that under kinetic control, the alternative reaction product, namely the hydride alkene isomer 2 a that derives from b-as opposed to a-hydride elimination in the last CÀH activation step, amounts to only about 5 % of the total reaction product (IrÀH signals at d = À20.40 for 1 and À17.49 ppm for 2 a, with intensity ratio of ca. 100:5

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Section: The Thermal Reaction Of Tpmentioning

confidence: 99%

A Measureable Equilibrium between Iridium Hydride Alkylidene and Iridium Hydride Alkene Isomers

et al. 2004

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“…Therefore, geometrical constraints arising from the metallacyclic structure of 3c,d are likely responsible for the preferred olefinic coordination of the vinylic ether fragment. As previously mentioned, [18] this (η 2 -olefine)metal ↔ (η 1 -carbene)metal tautomerism showed some similarity to (η 2 -alkyne)metal ↔ (η 1 -vinylidene)metal tautomerism and thus raised the analogous mechanistic question, as direct 1,2-hydrogen shift migration and transient formation of a hydrido vinyl-ruthenium(IV) intermediate are both conceivable.…”

Section: -Po-ph 2 Pch=c(tbu)o](co)mentioning

confidence: 66%

“…[17,18] In this case, a major role was devoted to the presence of the hydrido ligand, as the proposed mechanism consisted of insertion of the vinylic ether into the ruthenium-hydrogen bond and a subsequent α-elimination step (Scheme 2, path A). The lack of a hydrido ligand in complexes 3 and 5 obviously precluded an analogous (but reverse) mechanism to account for the 3 to 5 isomerization.…”

Section: -Po-ph 2 Pch=c(tbu)o](co)mentioning

confidence: 99%

“…Generation of a carbene ligand from vinylic ether (A) [17,18] and reversible deprotonation of a Fischer-type carbene ligand (B). [10] In contrast, a cyclic Fischer-type carbene ligand at a ruthenium centre could be deprotonated under basic conditions to generate a vinylic ruthenium complex and subsequently recovered under acidic conditions (Scheme 2, path B).…”

Section: -Po-ph 2 Pch=c(tbu)o](co)mentioning

confidence: 99%

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Reactivity of {Ru(C₅Me₅)[η²‐P,O‐Ph₂PCH₂C(tBu)=O](CO)}[PF₆] towards Terminal Alkynes and Unexpected Rearrangement of a Fischer‐Type Carbene Ligand

Demerseman¹,

Toupet²

2009

Eur J Inorg Chem

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The ruthenium complex {Ru(C5Me5)[η2‐P,O‐Ph2PCH2C(tBu)=O](CO)}[PF6] reacts with terminal alkynes HC≡CR (R = H, tBu, Ph) in methanol to afford {Ru[:C(OMe)CH2R](C5Me5)[η1‐P‐Ph2PCH2C(=O)tBu](CO)}[PF6] derivatives. The similar reaction conducted in dichloromethane as solvent led to six‐membered metallacyclic complexes{Ru(C5Me5)[η2‐C,P‐:C(CH2R)OC(tBu)=CH–PPh2](CO)}[PF6], which, when R is an aromatic group (R = Ph, p‐tolyl), rearrange under moderate thermal activation into {Ru(C5Me5)[η3‐C,C,P‐RCH=CH‐OC(tBu)=CHPPh2](CO)}[PF6] derivatives, according to an isomerization of a Fischer‐type carbene ligand into an η2‐coordinated vinylic ether, as shown by X‐ray single crystal analysis (R = p‐tolyl).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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“…The N3-C8 (6a: 1.184(5); 6b: 1.186(5)) and N1-C1 (6a: 1.178(5); 6b: 1.173(5)) bond lengths are however similar, and are set at the upper limit for a coordinated isocyano CN group when compared with those in the only two reported crystal structures R 2 R 1 BNCCr(CO) 5 [29][30][31][32] They both exhibit a partial C-N triple bond character. The isocyano carbon ruthenium distances Ru1-C1 and Ru1-C8 are shorter than the sum of the single-bond covalent radii (2.00 Å), 33 thus suggesting a partially double bond character [34][35][36][37][38][39] as a result of the metal-to-ligand π-back bonding that takes place more effectively towards the isocyanoborane trans to the cyano group and involving a deviation from linearity of the CN-B axis at the N atom. The nitrogen boron distances in 6a/6b (1.335 < NB < 1.495 Å) are in the range of values observed for amino substituted trigonal-planar boron groups.…”

Section: Dalton Transactions Papermentioning

confidence: 98%

Synthesis of a ruthenium bis(diisopropylamino(isocyano)borane) complex from the activation of an amino(cyano)borane

et al. 2013

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The reactivity of the amino(cyano)borane iPr2NBH(CN) (2) towards [RuH2(η2-H2)2(PCy3)2] (3) was investigated. Our study reveals that the formation of the bis(isocyanoborane) ruthenium complex [RuH(CN)(CN-BHNiPr2)2(PCy3)2] (6) occurs via the intermediacy of the bis(σ-B–H) ruthenium complex [RuH(CN)(H2BNiPr2)(PCy3)2] (5). This transformation involves BCN linkage isomerisation in 2. The diisopropylaminoborane ligand in 5 can be displaced to ultimately produce the bis(σ-borane) complex [RuH2(η2:η2-H2BNiPr2)(PCy3)2] (4) as a by-product

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Coordinated carbenes from electron-rich olefins on RuHCl(PPr3i)2

Cited by 87 publications

References 20 publications

A Measureable Equilibrium between Iridium Hydride Alkylidene and Iridium Hydride Alkene Isomers

A Measureable Equilibrium between Iridium Hydride Alkylidene and Iridium Hydride Alkene Isomers

Reactivity of {Ru(C₅Me₅)[η²‐P,O‐Ph₂PCH₂C(tBu)=O](CO)}[PF₆] towards Terminal Alkynes and Unexpected Rearrangement of a Fischer‐Type Carbene Ligand

Synthesis of a ruthenium bis(diisopropylamino(isocyano)borane) complex from the activation of an amino(cyano)borane

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Coordinated carbenes from electron-rich olefins on RuHCl(PPr3i)2

Cited by 87 publications

References 20 publications

A Measureable Equilibrium between Iridium Hydride Alkylidene and Iridium Hydride Alkene Isomers

A Measureable Equilibrium between Iridium Hydride Alkylidene and Iridium Hydride Alkene Isomers

Reactivity of {Ru(C5Me5)[η2‐P,O‐Ph2PCH2C(tBu)=O](CO)}[PF6] towards Terminal Alkynes and Unexpected Rearrangement of a Fischer‐Type Carbene Ligand

Synthesis of a ruthenium bis(diisopropylamino(isocyano)borane) complex from the activation of an amino(cyano)borane

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Reactivity of {Ru(C₅Me₅)[η²‐P,O‐Ph₂PCH₂C(tBu)=O](CO)}[PF₆] towards Terminal Alkynes and Unexpected Rearrangement of a Fischer‐Type Carbene Ligand