ChemInform Abstract: REACTIONS OF COORDINATED LIGANDS. PART 27. FORMATION OF η3‐ALLYL AND Σ‐VINYL COMPLEXES BY NUCLEOPHILIC ATTACK ON CATIONIC MOLYBDENUM MONOACETYLENE COMPLEXES. MOLECULAR STRUCTURES OF CARBONYL(η5‐INDENYL)(η3‐ANTI‐1‐METHYLALLYL)(TRIETHYLPHOSPHINE)MOLYBDENU# M(II) AND (Σ‐(E)‐2‐TERT‐BUTYLVINYL)(η‐CYCLOPENTADIENYL)TRIS(TRIMETHYL PHOSPHITE)MOLYBDENUM(II)

Allen, Stephen; Baker, Paul K.; Barnes, Stephen G.; Bottrill, M.; Green, M.; Orpen, A. Guy; Williams, Ian D.; Welch, Alan J.

doi:10.1002/chin.198334276

Cited by 2 publications

(2 citation statements)

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“…The transformation of alkynes into allyl ligands at the coordination sphere of late transition-metal complexes is key for certain catalytic functionalizations affording branched structures. , A possible mechanism via hydrido-allene intermediates was suggested by Werner and Wolf in Rh(Cp) complexes following early proposals by Green et al in Mo derivatives. , Figure summarizes the free energy profile corresponding to this mechanism in benzene, starting from the first observable intermediate 5 ( [5 calc fac ] + ) and finishing in the final reaction product at room temperature 2 ( [2 calc ] + ). The highest barrier in this profile is 24.6 kcal mol –1 , hence compatible with a room temperature reaction.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Versatility at Ir(PSiP) Pincer Catalysts: Triflate Proton Shuttling from 2-Butyne to Diene and [3]Dendralene Motifs

et al. 2022

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The five-coordinate hydrido complex [IrH(OTf)(PSiP)] ( 1 ) catalytically transforms 2-butyne into a mixture of its isomer 1,3-butadiene, and [3]dendralene and linear hexatriene dimerization products: ( E )-4-methyl-3-methylene-1,4-hexadiene and (3 Z )-3,4-dimethyl-1,3,5-hexatriene, respectively. Under the conditions of the catalytic reaction, benzene, and 363 K, the hexatriene further undergoes thermal electrocyclization into 2,3-dimethyl-1,3-cyclohexadiene. The reactions between 1 and the alkyne substrate allow isolation or nuclear magnetic resonance (NMR) observation of catalyst resting states and possible reaction intermediates, including complexes with the former PSiP pincer ligands disassembled into PSi and PC chelates, and species coordinating allyl or carbene fragments en route to products. The density functional theory (DFT) calculations guided by these experimental observations disclose competing mechanisms for C–H bond elaboration that move H atoms either classically, as hydrides, or as protons transported by the triflate. This latter role of triflate, previously recognized only for more basic anions such as carboxylates, is discussed to result from combining the unfavorable charge separation in the nonpolar solvent and the low electronic demand from the metal to the anion at coordination positions trans to silicon. Triflate deprotonation of methyl groups is key to release highly coordinating diene products from stable allyl intermediates, thus enabling catalytic cycling.

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Section: Resultsmentioning

confidence: 99%

Mechanistic Versatility at Ir(PSiP) Pincer Catalysts: Triflate Proton Shuttling from 2-Butyne to Diene and [3]Dendralene Motifs

et al. 2022

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“…An interesting reactivity was observed when [CpMo (η 2 -C 2 R 2 )L 2 ]BF 4 was reacted with a hydride reagent giving η 3 -vinyl complexes presumably through isomerization of the vinyl intermediates. [27] Notably, the complex [(η 5 -indenyl)Mo(Me 3 SiC�CH)(P(OMe) 3 ) 2 ]BF 4 reacts with a hydride nucleophile leading to an unstable η 2 -vinyl complex which quantitatively rearranges to the alkylidyne complex [(η 5 -indenyl) Mo(CCH 2 SiMe 3 )(P(OMe) 3 ) 2 ]. [28] The only examples of the reactivity of group six metal complexes with coordinated C 2 H 2 were very recently reported by our group.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Reactivity of Molybdenum and Tungsten Alkyne Complexes Containing 6‐Methylpyridine‐2‐thiolate Ligands

Ehweiner

Ćorović

Belaj

et al. 2021

Helvetica Chimica Acta

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A series of M(II) and M(IV) (M = Mo, W) alkyne adducts employing two 6-methylpyridine-2-thiolate (6-MePyS) ligands was synthesized and investigated towards the nucleophilic attack of PMe 3 on the coordinated alkynes. For this approach, 2-butyne (C 2 Me 2 ), phenylacetylene (HC 2 Ph), and diphenylacetylene (C 2 Ph 2 ) were used. For the exploration of an intramolecular attack, but-3-yn-1-ol (HCCCH 2 CH 2 OH) was coordinated to the metal centers. A nucleophilic attack of PMe 3 was observed in [W(CO)(HC 2 Ph)(6-MePyS) 2 ] yielding an η 2 -vinyl compound. Reaction of [W(CO)(C 2 Ph 2 )(6-MePyS) 2 ] with excess PMe 3 resulted in the selective coordination of one molecule of PMe 3 concomitant with decoordination of the nitrogen atom of one 6-MePyS ligand. In contrast, the W(IV) complexes did not react with PMe 3 . While no selectivity was observed in the reaction of the Mo(II) compounds with PMe 3 , alkynes in the Mo(IV) compounds were replaced by PMe 3 . Addition of Et 3 N to the but-3-yn-1-ol complexes did not lead to the anticipated formation of 2,3-dihydrofuran.

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Cited by 2 publications

References 1 publication

Mechanistic Versatility at Ir(PSiP) Pincer Catalysts: Triflate Proton Shuttling from 2-Butyne to Diene and [3]Dendralene Motifs

Mechanistic Versatility at Ir(PSiP) Pincer Catalysts: Triflate Proton Shuttling from 2-Butyne to Diene and [3]Dendralene Motifs

Synthesis and Reactivity of Molybdenum and Tungsten Alkyne Complexes Containing 6‐Methylpyridine‐2‐thiolate Ligands

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