Activation of propargylic alcohols by dimolybdenum tris(μ-thiolate) complexes: Influence of the substituents R in HCCCR2(OH)-vinylidene/allenylidene transformation. Reactivity of allenylidene complexes

Ojo, Wilfried-Solo; Capon, Jean‐François; Goff, Alan Le; Pétillon, François Y.; Schollhammer, Philippe; Talarmin, Jean; Muir, Kenneth W.

doi:10.1016/j.jorganchem.2007.08.023

Cited by 8 publications

(4 citation statements)

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“…When 1,1-diphenyl-2-propyn-1-ol was used, the reaction gave the allenylidene complex 20 in good yield, via a μ-alkynyl derivative, implying a four-step process (Scheme ) . However, the reaction of [Mo 2 Cp 2 (μ-SMe) 3 (NCMe) 2 ][BF 4 ] with HCCC(OH)Me 2 in the presence of HBF 4 ·OEt 2 (1 equiv) led to a complex mixture of several dinuclear complexes containing the corresponding allenylidene complex [Mo 2 Cp 2 (μ-SMe) 3 (μ-η 1 :η 2 CCCMe 2 )][BF 4 ] as a minor component …”

Section: Preparation Of Allenylidene Complexesmentioning

confidence: 99%

“…Addition of anionic nucleophiles Nu − (H − , MeO − , HO − , MeS − ) to the dinuclear molybdenum−allenylidene complex [Mo 2 Cp 2 (μ-SMe) 3 (μ-η 1 :η 2 CC=CMe 2 )][BF 4 ] ( 20 in Scheme ), affording the corresponding neutral acetylide derivatives [Mo 2 Cp 2 (μ-SMe) 3 {μ-η 1 :η 2 -CCC(Nu)Ph 2 }], has also been described …”

Section: Reactivity Of Allenylidene Complexesmentioning

confidence: 99%

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Allenylidene and Higher Cumulenylidene Complexes

2009

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Section: Preparation Of Allenylidene Complexesmentioning

confidence: 99%

Section: Reactivity Of Allenylidene Complexesmentioning

confidence: 99%

Allenylidene and Higher Cumulenylidene Complexes

2009

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“…The complex achieves a closed-shell configuration if the ligand is viewed as a monocarbene, as depicted by the two extreme forms in Chart . The Mo1−Mo2 distance of 2.7254(7) Å is comparable to that of 2.705(7) Å in the cation [Mo 2 Cp 2 (μ-SMe) 3 (μ-η 1 :η 1 -HCCCO 2 Me)] + , hence indicating a single bond. We consider that the X-ray study establishes 7 as a μ-η 1 (C):η 1 (C) complex and therefore formulate 7 as a dimetallaimidoyl(amino)carbene derivative, with a parallel orientation of the C−C axis of the coupled ligand relative to that of the Mo−Mo bond (C4−C5−Mo1−Mo2 torsion angle 1.2(3)°).…”

Section: Resultsmentioning

confidence: 77%

C−C, C−S, and C−N Coupling versus Dealkylation Processes in the Cationic Tris(thiolato)dimolybdenum(III) Complexes [Mo₂Cp₂(μ-SMe)₃L₂]⁺ (L = xylNC, t-BuNC, CO, MeCN)

et al. 2008

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Reductive coupling between isocyanide ligands attached to adjacent molybdenum atoms in the bis(aryl isocyanide) complex [Mo2Cp2(μ-SMe)3(xylNC)2](BF4) (1) was initiated by addition of the hydrosulfide anion (HS−) to 1 under reflux in tetrahydrofuran, affording, in nearly quantitative yields, the dimetallaimidoyl(amino)carbene derivative [Mo2Cp2(μ-SMe)3{μ-η1(C):η1(C)-C(NHxyl)C(Nxyl)}] (7), in which both isocyanide groups of 1 are now linked by a new C−C bond. When the previous reaction was conducted in the presence of a large excess of hydrosulfide (20 equiv), under similar experimental conditions, the dithiocarbonimidate compound [Mo2Cp2(μ-SMe)2(μ-S2CNxyl)] (8) was obtained in quantitative yields. This product results from subsequent thiolate exchange and substitution reactions to afford a quadruply sulfur bridged intermediate, followed by free isonitrile addition to sulfido S atoms. Treatment of the coupled isocyanide derivative 7 with HBF4 led exclusively to the formation of the starting complex 1 by reversible isocyanide ligand decoupling. The heating of a tetrahydrofuran solution of 1 with the base NaCCH gave, in high yields, the μ-alkylidyne and μ-acetylide product [Mo2Cp(μ-SMe)2{μ-(η5-C5H4)(xylN)CN(xyl)C}(μ-CCH)] (9), in which a deprotonated Cp and both isocyanide ligands of 1 are now linked by new C−C and C−N bonds, and in addition an acetylide has replaced a thiolate ligand of 5. Reaction of the μ-alkylidyne complex [Mo2Cp(μ-SMe)3{μ-(η5-C5H4)(xylN)CN(xyl)C}] (5) with NaCCH under reflux in tetrahydrofuran produced, in high yields, the μ-alkylidyne and bis(μ-acetylide) cationic compound [Mo2Cp(μ-SMe)2{μ-(η5-C5H4)(xylN)CN(xyl)C}(μ-CCH)2]Br (10), in which two xylNC ligands have replaced a thiolate group of 5. Further reactions of the bis(μ-isocyanide) complex 10 with NaOH (suspension), on the one hand, and HBF4, on the other hand, under reflux in tetrahydrofuran or at room temperature in dichloromethane, respectively, led to the formation in high yields of the known mixed μ-alkylidyne and μ-amino-oxycarbene species [Mo2Cp(μ-SMe)2{μ-(η5-C5H4)(xylN)CN(xyl)C}{μ-η1(O):η1(C)-OCNHxyl}] (12) and the new tetrakis(isocyanide) dicationic derivative [Mo2Cp2(μ-SMe)2(xylNC)4](BF4)2 (11), respectively. The latter complex results from successive protonation at one carbon atom of the cyclopentadienyl ligand linked with isocyanides of 10 and decoupling between deprotonated Cp and isocyanide ligands. The heating of a tetrahydrofuran solution of a mixture of the bis(alkyl isocyanide) complex [Mo2Cp2(μ-SMe)3(t-BuNC)2](BF4) (2) and NaSH proceeded exclusively through the dealkylation of one tert-butyl isocyanide ligand to afford the known product [Mo2Cp2(μ-SMe)3(t-BuNC)](CN)] (13). Similar reaction of the dicarbonyl derivative [Mo2Cp2(μ-SMe)3(CO)2]Cl (3) with NaSH proceeded through dealkylation of one thiolate group to yield the new neutral sulfido species [Mo2Cp2(μ-SMe)2(μ-S)(CO)2] (14). Further heating of 14 in dichloromethane led to the formation of the chloromethanethiolate derivative [Mo2Cp2(μ-SMe)2(μ-SCH2Cl)(CO)2]Cl (15)...

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“…Their investigation advanced significantly when Selegue found in 1982 that they can be accessed from corresponding (activated) precursor complexes and propargylic alcohols 1 (Scheme ) . Since then, a number of stable allenylidene complexes have been isolated, mainly based on ruthenium, , but also for other metals such as palladium, chromium, molybdenum, osmium, or iron . Allenylidene complexes exhibit interesting optical and electrochemical properties .…”

Section: Introductionmentioning

confidence: 99%

Diastereoselective Attack on Chiral-at-Metal Ruthenium Allenylidene Complexes To Give Alkynyl Complexes

2014

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New chiral ruthenium(II) allenylidene complexes were synthesized, and their reactivity with nucleophiles to give alkynyl complexes was investigated. The new allenylidene complex (R Ru ,R ax )-[Ru(Ind)(PPh 3 )(6){C CC(t-Bu)(2-naphthyl)}] + PF 6 − was synthesized from the chloro precursor complex (R Ru ,R ax )-[RuCl(Ind)(PPh 3 )( 6)] and the racemic propargylic alcohol HCCC(OH)(t-Bu)(2naphthyl) and obtained in 96% yield, where (R ax )-6 is a chiral phosphoramidite and Ind an anionic indenyl ligand. The precursor and the allenylidene complex are chiral-at-metal, and the chiral information is completely transferred from the chloro precursor to the product allenylidene complex, both of which show the same absolute configuration, as demonstrated by X-ray diffraction. Together with the known allenylidene complex (R Ru ,R ax )-[Ru(Ind)(PPh 3 )(6)(CCCPh 2 )] + PF 6 − , the attack of n-BuLi, MeLi, LiCCPh, and lithium 1-phenylethenolate nucleophiles on the allenylidene chain of (R Ru ,R ax )-[Ru(Ind)(PPh 3 )-( 6){CCC(t-Bu)(2-naphthyl)}] + PF 6 − was investigated. The nucleophiles (Nu) reacted selectively with the gamma carbon of the allenylidene complexes to give the alkynyl complexes (R Ru ,R ax )-[Ru(Ind)(PPh 3 )(6)(CC−CPh 2 Nu)] and (R Ru ,R ax )-[Ru(Ind)(PPh 3 )(6){CC−C(t-Bu)(2-naphthyl)Nu}] in 40% to 96% isolated yields. In the case of (R Ru ,R ax )-[Ru(Ind)(PPh 3 )-(6){CC−C*(t-Bu)(2-naphthyl)Nu}], the gamma carbon C* becomes stereogenic upon attack of the nucleophiles. As assessed by 31 P{ 1 H} NMR, diastereodifferentiation took place, and the alkynyl complexes were isolated as diastereomeric mixtures with diastereomeric ratios between 60:40 and 84:16. The diastereodifferentiation originated only from the stereogenic metal center and the monodentate, chiral ligand. The study allows for investigation of stereoselective, nucleophilic attack of allenylidene complexes to give optically active, quaternary alkynes, which play a role in potential catalytic versions of nucleophilic substitution reactions of propargylic alcohols.

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Activation of propargylic alcohols by dimolybdenum tris(μ-thiolate) complexes: Influence of the substituents R in HCCCR2(OH)-vinylidene/allenylidene transformation. Reactivity of allenylidene complexes

Cited by 8 publications

References 83 publications

Allenylidene and Higher Cumulenylidene Complexes

Allenylidene and Higher Cumulenylidene Complexes

C−C, C−S, and C−N Coupling versus Dealkylation Processes in the Cationic Tris(thiolato)dimolybdenum(III) Complexes [Mo₂Cp₂(μ-SMe)₃L₂]⁺ (L = xylNC, t-BuNC, CO, MeCN)

Diastereoselective Attack on Chiral-at-Metal Ruthenium Allenylidene Complexes To Give Alkynyl Complexes

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Activation of propargylic alcohols by dimolybdenum tris(μ-thiolate) complexes: Influence of the substituents R in HCCCR2(OH)-vinylidene/allenylidene transformation. Reactivity of allenylidene complexes

Cited by 8 publications

References 83 publications

Allenylidene and Higher Cumulenylidene Complexes

Allenylidene and Higher Cumulenylidene Complexes

C−C, C−S, and C−N Coupling versus Dealkylation Processes in the Cationic Tris(thiolato)dimolybdenum(III) Complexes [Mo2Cp2(μ-SMe)3L2]+ (L = xylNC, t-BuNC, CO, MeCN)

Diastereoselective Attack on Chiral-at-Metal Ruthenium Allenylidene Complexes To Give Alkynyl Complexes

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C−C, C−S, and C−N Coupling versus Dealkylation Processes in the Cationic Tris(thiolato)dimolybdenum(III) Complexes [Mo₂Cp₂(μ-SMe)₃L₂]⁺ (L = xylNC, t-BuNC, CO, MeCN)