Preparation and Stoichiometric Reactivity of Mononuclear Metal Vinylidene Complexes

Bruce, Michael I.

doi:10.1002/9783527622870.ch1

Cited by 6 publications

(7 citation statements)

References 375 publications

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“…They are also remarkably different in stability: whereas the π-alkyne compounds are stable under an inert atmosphere, the alkynyl ketone adducts undergo spontaneous isomerization to vinylidene both in solution and in the solid state. It is noteworthy that π-alkyne complexes are generally described as reasonable intermediates in the first step of the alkyne–vinylidene isomerization, which has been shown to be the case in the isomerization of terminal alkynes. − , …”

Section: Resultsmentioning

confidence: 99%

“…It is well-known that the relative stability of alkyne and vinylidene isomers is reversed upon coordination to a variety of transition metals. This process (HCCR → :CCHR) is the main synthetic route to vinylidene species , and is a key step for several catalytic alkyne transformations . The simplest role of the metal is to stabilize the vinylidene lone pair of electrons by means of a dative carbon→metal bond, throughout a concerted 1,2-H rearrangement.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, electron-poor dicarbonyl systems such as [CpFe(CO) 2 (CCRR′)] + (R, R′ = Me, Ph) spontaneously undergo isomerization to π-alkyne complexes . Intermediate situations have led to the observation of vinylidene/π-alkyne equilibria and to reversible alkyne/vinylidene isomerization, which is essential for several catalytic reactions via vinylidene intermediates …”

Section: Introductionmentioning

confidence: 99%

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Internal Alkyne Isomerization to Vinylidene versus Stable π-Alkyne: Theoretical and Experimental Study on the Divergence of Analogous Cp*Ru and TpRu Systems

et al. 2011

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The activation of internal alkynes by Cp*Ru and TpRu complexes gives respectively π-alkyne and disubstituted vinylidene as stable species, even though both systems bear identical pyridylphosphine ligands (k 2 P,N-i Pr 2 PXPy, X = NH, CH 2 , S). The activation of the alkynones PhCtCCOR (R = Me, Ph) by [TpRuCl( i Pr 2 PXPy)] complexes allowed us to isolate and characterize metastable η 1 -OdC(R)CtCPh adducts. These complexes isomerize spontaneously to vinylidene both in solution and in the solid state. Kinetic studies have been carried out in solution by 31 P{ 1 H} NMR and in the solid state by IR spectroscopy, providing the Eyring and AvramiÀErofeev parameters, respectively. The activation of internal alkynes without ketone groups provided vinylidene species as well, but without isolable intermediates. In contrast with the TpRu system, the activation of alkynones by [Cp*RuCl( i Pr 2 PXPy)] always results in stable π-alkyne species. Representatives of both Cp*RuÀπ-alkyne and TpRuÀvinylidene compounds have been characterized by X-ray diffraction. DFT calculations have been carried out with the actual experimental complexes, including solvent effects, in order to analyze the mechanism of the π-alkyne to vinylidene isomerization of internal alkynes and to explain the divergent results obtained for Tp and Cp*.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Internal Alkyne Isomerization to Vinylidene versus Stable π-Alkyne: Theoretical and Experimental Study on the Divergence of Analogous Cp*Ru and TpRu Systems

et al. 2011

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“…The alkylation proceeded exclusively at the oxygen atom. The addition of electrophiles to the C β atom of (neutral or anionic) alkynyl complexes has turned out to be a convenient route to vinylidene complexes . However, in the reactions of 2a , b with “Me + ” there was no indication for an addition of the electrophile to the C β atom of either one or both alkynyl ligands.…”

Section: Resultsmentioning

confidence: 99%

Bis(allenylidene) Complexes of Palladium and Platinum

2010

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trans-Bis(alkynyl)palladium complexes, trans-[(PEt 3) 2 Pd(-CtCC{dO}NR 2) 2 ] (NR 2 = NMe 2 (2a), N(CH 2) 4 (2b)), were synthesized by two different methods: (a) by copper-catalyzed reaction of HCtCC(dO)NR 2 with [PdCl 2 (PEt 3) 2 ] under basic conditions and (b) by treating HCtCC(dO)NR 2 with AgNO 3 followed by transmetalation of the alkynyl ligand from silver to [PdCl 2 (PEt 3) 2 ]. The reaction of AgCtCC(dO)NMe 2 (3a) with trans-[Br(P i Pr 3) 2 PdCtCC(dO)N(CH 2) 4 ] (5) affords a complex containing two different alkynyl ligands, trans-[(P i Pr 3) 2 Pd{-CtCC(dO)NMe 2 }{-CtCC-(dO)N(CH 2) 4 }] (6). Methylation of 2a,b and 6 with MeOTf or [Me 3 O]BF 4 yields dicationic bisallenylidene complexes of palladium, trans-[(PEt 3) 2 Pd{dCdCdC(OMe)NR 2 } 2 ] 2þ 2X (X = OTf, BF 4 ; NR 2 = NMe 2 , N(CH 2) 4) and trans-[(PEt 3) 2 Pd{dCdCdC(OMe)NMe 2 }{dCdCdC-(OMe)N(CH 2) 4 }] 2þ 2OTf (7-OTf). In contrast to the reaction of 3a with [PdCl 2 (PEt 3) 2 ], that of 3a with the platinum complex [PtCl 2 (PPh 3) 2 ] gives cisand trans-[(PPh 3) 2 Pt(-CtCC{dO}NMe 2) 2 ] (8a (cis) and 9a (trans)), depending on the reaction conditions and, upon subsequent alkylation with MeOTf, the cis and trans isomers of the first allenylidene platinum complexes, cisand trans-[(PPh 3) 2 Pt{dCdCdC(OMe)NMe 2 } 2 ] 2þ 2OTf .

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“…The success of the CuAAC reaction further highlighted the need for regioselective formation of 1,5-substituted triazoles. Since catalytic transformations of alkynes via the action of ruthenium (Ru) complexes have been established, − various Ru catalysts were evaluated and shown to be capable of catalyzing the regioselective formation of 1,5-substituted triazoles. ,, Ru catalysis is advantageous over Cu in that it allows the reaction between internal alkynes and azides . Despite this benefit, steric and electronic considerations of the 1,5-triazole become important.…”

Section: Azide–alkyne Cycloaddition Reactionmentioning

confidence: 99%

Practical Considerations, Challenges, and Limitations of Bioconjugation via Azide–Alkyne Cycloaddition

et al. 2017

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Interrogating biological systems is often limited by access to biological probes. The emergence of "click chemistry" has revolutionized bioconjugate chemistry by providing facile reaction conditions amenable to both biologic molecules and small molecule probes such as fluorophores, toxins, or therapeutics. One particularly popular version is the copper-catalyzed azide-alkyne cycloaddition (AAC) reaction, which has spawned new alternatives such as the strain-promoted azide-alkyne cycloaddition reaction, among others. This focused review highlights practical approaches to AAC reactions for the synthesis of peptide or protein bioconjugates and contrasts current challenges and limitations in light of recent advances in the field. The conical success of antibody drug conjugates has expanded the toolbox of linkers and payloads to facilitate practical applications of bioconjugation to create novel therapeutics and biologic probes. The AAC reaction in particular is poised to enable a large set of functionalized molecules as a combinatorial approach to high-throughput bioconjugate generation, screening, and honing of lead compounds.

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Preparation and Stoichiometric Reactivity of Mononuclear Metal Vinylidene Complexes

Cited by 6 publications

References 375 publications

Internal Alkyne Isomerization to Vinylidene versus Stable π-Alkyne: Theoretical and Experimental Study on the Divergence of Analogous Cp*Ru and TpRu Systems

Internal Alkyne Isomerization to Vinylidene versus Stable π-Alkyne: Theoretical and Experimental Study on the Divergence of Analogous Cp*Ru and TpRu Systems

Bis(allenylidene) Complexes of Palladium and Platinum

Practical Considerations, Challenges, and Limitations of Bioconjugation via Azide–Alkyne Cycloaddition

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