Oxidative dehydrodimerization of manganese phenylvinylidene complex (η5-C5H5)(CO)2MnCC(H)Ph. X-ray structure of phenyl(trityl)vinylidene complex (η5-C5H5)(CO)2MnCC(CPh3)Ph

Novikova, L. N.; Peterleitner, M. G.; Sevumyan, Karine A.; Semeikin, Oleg V.; Valyaev, Dmitry A.; Ustynyuk, Nikolai A.; Khrustalev, Victor N.; Kuleshova, L. N.; Antipin, M. Yu.

doi:10.1016/s0022-328x(01)01030-0

Cited by 28 publications

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“…To gain some further insight and evidence for this concept of a deprotonation/remote re‐protonation conceptually illustrated in Scheme , we turned attention to the model reactions of the metal acetylide complexes [M(C≡C‐1,4‐C 6 H 4 ‐C≡CH)(LL)Cp’] ( 4 a–d ) with electrophiles. The prototypical ethynyl‐substituted phenyl acetylide complex [Ru(C≡C‐1,4‐C 6 H 4 ‐C≡CH)(PPh 3 ) 2 Cp] ( 4 a ) was allowed to react with electrophiles of increasing steric demand, specifically 1‐cyano‐4‐dimethylaminopyridinium tetrafluoroborate ([CAP]BF 4 ) as a convenient source of cyanogen, [CN] + , tropylium tetrafluoroborate ([C 7 H 7 ]BF 4 ) and trityl tetrafluoroborate ([CPh 3 ]BF 4 ) . Whilst both [CAP]BF 4 and [C 7 H 7 ]BF 4 afforded the anticipated vinylidene complexes [Ru{C=C(CN)‐1,4‐C 6 H 4 ‐C≡CH}(PPh 3 ) 2 Cp]BF 4 ([ 5 a‐CN ]BF 4 ) and [Ru{C=C(C 7 H 7 )‐1,4‐C 6 H 4 ‐C≡CH}(PPh 3 ) 2 Cp]BF 4 ([ 5 a‐C 7 H 7 ]BF 4 ), the reaction of 4 a with the very bulky trityl electrophile gave Ru{C≡C‐1,4‐C 6 H 4 ‐C(=O)CH 2 CPh 3 }(PPh 3 ) 2 Cp ( 6 a ) after workup (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Hall

Steen

Korb

et al. 2020

Chemistry A European J

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Reactions of [Ru{C=C(H)‐1,4‐C6H4C≡CH}(PPh3)2Cp]BF4 ([1 a]BF4) with hydrohalic acids, HX, results in the formation of [Ru{C≡C‐1,4‐C6H4‐C(X)=CH2}(PPh3)2Cp] [X=Cl (2 a‐Cl), Br (2 a‐Br)], arising from facile Markovnikov addition of halide anions to the putative quinoidal cumulene cation [Ru(=C=C=C6H4=C=CH2)(PPh3)2Cp]+. Similarly, [M{C=C(H)‐1,4‐C6H4‐C≡CH}(LL)Cp ]BF4 [M(LL)Cp’=Ru(PPh3)2Cp ([1 a]BF4); Ru(dppe)Cp* ([1 b]BF4); Fe(dppe)Cp ([1 c]BF4); Fe(dppe)Cp* ([1 d]BF4)] react with H+/H2O to give the acyl‐functionalised phenylacetylide complexes [M{C≡C‐1,4‐C6H4‐C(=O)CH3}(LL)Cp’] (3 a–d) after workup. The Markovnikov addition of the nucleophile to the remote alkyne in the cations [1 a–d]+ is difficult to rationalise from the vinylidene form of the precursor and is much more satisfactorily explained from initial isomerisation to the quinoidal cumulene complexes [M(=C=C=C6H4=C=CH2)(LL)Cp’]+ prior to attack at the more exposed, remote quaternary carbon. Thus, whilst representative acetylide complexes [Ru(C≡C‐1,4‐C6H4‐C≡CH)(PPh3)2Cp] (4 a) and [Ru(C≡C‐1,4‐C6H4‐C≡CH)(dppe)Cp*] (4 b) reacted with the relatively small electrophiles [CN]+ and [C7H7]+ at the β‐carbon to give the expected vinylidene complexes, the bulky trityl ([CPh3]+) electrophile reacted with [M(C≡C‐1,4‐C6H4‐C≡CH)(LL)Cp’] [M(LL)Cp’=Ru(PPh3)2Cp (4 a); Ru(dppe)Cp* (4 b); Fe(dppe)Cp (4 c); Fe(dppe)Cp* (4 d)] at the more exposed remote end of the carbon‐rich ligand to give the putative quinoidal cumulene complexes [M{C=C=C6H4=C=C(H)CPh3}(LL)Cp’]+, which were isolated as the water adducts [M{C≡C‐1,4‐C6H4‐C(=O)CH2CPh3}(LL)Cp’] (6 a–d). Evincing the scope of the formation of such extended cumulenes from ethynyl‐substituted arylvinylene precursors, the rather reactive half‐sandwich (5‐ethynyl‐2‐thienyl)vinylidene complexes [M{C=C(H)‐2,5‐cC4H2S‐C≡CH}(LL)Cp’]BF4 ([7 a–d]BF4 add water readily to give [M{C≡C‐2,5‐cC4H2S‐C(=O)CH3}(LL)Cp’] (8 a–d)].

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Section: Resultsmentioning

confidence: 99%

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Hall

Steen

Korb

et al. 2020

Chemistry A European J

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“…Coupling in the usual C β -C β fashion gives the bis(carbyne) [CpЈ(CO) 2 -MnϵC-C(Ph)=C(Ph)-CϵMn(CO) 2 CpЈ] 2+ , which in turn can be reversibly reduced to the neutral bis(vinylidene). [104] The oxidative dehydrodimerisation of the more electronrich systems featuring L = PPh 3 or CpЈ = Cp* supporting ligands proceeds by a sequence of oxidation and C β -C β coupling to give a species closely related to 14 with subsequent proton loss resulting in the formation of a neutral…”

Section: Cpј]mentioning

confidence: 99%

Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes

Schauer

Low

2011

Eur J Inorg Chem

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Transition-metal σ-alkynyl complexes are valuable functional materials that have found application as sructural units in the assembly of polymetallic arrays and large molecular structures, reagents for the transfer, oligomerisation or functionalisation of alkynes, magnetic or optical materials and putative components for use in a future molecular-based electronics platform. Many σ-alkynyl complexes are redoxactive, undergoing facile oxidation (reduction) at moderate potentials to generate radical cations (anions) in which the

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“…8 We have recently shown 9 that oxidative dehydrodimerization of the manganese vinylidene complex (Z involves the formally 16-e mononuclear s-phenylethynyl cation 2 and the bis-carbyne dication 4 as the key sequential intermediates (see Scheme 1). A similar scheme was also reported for (Z 5 -C 5 H 4 Me)(dmpe)Mn=C=CHPh.…”

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confidence: 99%

Oxidative dehydrodimerization of manganese vinylidene complexes (η⁵‐C₅R₅)(CO)(L)MnCCHPh (R = Me, L = CO; R = H, L = PPh₃)

Novikova

Peterleitner

Sevumyan

et al. 2002

Applied Organom Chemis

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The oxidative dehydrodimerization of the phenylvinylidene manganese complexes (Z 5 -C 5 R 5 )(CO)(L)Mn=C=CHPh (5: R=Me, L=CO; 6: R=H, L=PPh 3 ) into the corresponding bisvinylidene compounds (Z 5 -C 5 R 5 )(CO)(L)Mn=C=CPhÐCPh=C=Mn(CO)(L)(Z 5 -C 5 R 5 ) (7: R=Me, L=CO; 8: R=H, L=PPh 3 ) was studied by cyclic voltammetry and chemical experiments. It was found that dehydrodimerization of 5 and 6 proceeds via direct C (b) ÐC (b) In this paper we report on the oxidative dehydrodimerization of manganese vinylidene complexes (Z 5 -C 5 R 5 )(CO)(L)Mn=C=CHPh (5: R=Me, L=CO; 6: R=H, L=PPh 3 ). Despite 5 and 6 having a close similarity to 1, their dehydrodimerization proceeds according to a different scheme, as will be shown below. (7) was carried out using a procedure similar to that for 1, 9 i.e. 5 was oxidized by AgBF 4 in dichloromethane at À40°C, the solution was kept at this temperature for 2 h and finally reduced by (Z-C 6 H 6 ) 2 Cr. The target complex 7 was obtained in 40% yield and characterized by 1 H and 13 C NMR spectroscopy as well as by mass spectrometry. We found that the yield of 7 can be increased to 85±90% if either potassium t-butylate or triethylamine is used in the final reaction step. In order to determine the mechanism of the dehydrodimerization process, we studied the electrochemical behavior of complexes 5 and 7 by cyclic voltammetry in CH 2 Cl 2 solution (see Table 1).Complex 7 displays two one-electron reversible oxidation waves at 0.17 V (peak A) and 0.58 V (peak B) (see Fig. 1). Complex 5 oxidizes irreversibly at 0.77 V (see Fig. 2, peak C). The reverse scanning of potentials revealed new cathodic peaks at 0.67 V and 0.27 V (peaks D and E respectively). These peaks do not coincide with the reduction peaks A', B' of 7 .Thus, 7 is not an initial product of transformation of 5 Á ,i.e. dehydrodimerization of 5 proceeds by a different mechanism than that for complex 1 (Scheme 1). We believe Scheme 1.Scheme 2. Figure 1. CV of bis-vinylidene complex 7 at 20°C. ). In order to confirm the validity of the mechanism shown in Scheme 3, we studied the oxidative dehydrodimerization of the triphenylphosphine-substituted phenylvinylidene complex (Z 5 -C 5 H 5 )(CO)(PPh 3 )Mn=C=CHPh (6), since we expected the product of direct C (b) ÐC (b) that the isomers differ in the orientation of the phenyl group relative to the cyclopentadienyl ring. Oxidative dehydrodimerization of 6 was carried out under the same conditions as the analogous processes for 1 and 5. The bis-vinylidene complex 8 proved to be rather unstable, and was obtained in 20% yield. Its structure was confirmed by IR-, NMR 1 H, and 31 P spectroscopy and mass spectroscopy. According to the NMR spectra, complex 8 exists as a mixture of two diastereomers in 3:1 ratio.Electrochemical oxidation of 6 and 8 was studied by cyclic voltammetry (CV) in dichloromethane solution. The cyclic voltammogram of the bis-vinylidene complex 8 showed two reversible one-electron oxidation peaks at 0.19 V and 0.61 V (Fig. 3, peaks F and G respectively). The cyclic voltam...

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Oxidative dehydrodimerization of manganese phenylvinylidene complex (η5-C5H5)(CO)2MnCC(H)Ph. X-ray structure of phenyl(trityl)vinylidene complex (η5-C5H5)(CO)2MnCC(CPh3)Ph

Cited by 28 publications

References 24 publications

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes

Oxidative dehydrodimerization of manganese vinylidene complexes (η⁵‐C₅R₅)(CO)(L)MnCCHPh (R = Me, L = CO; R = H, L = PPh₃)

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Oxidative dehydrodimerization of manganese phenylvinylidene complex (η5-C5H5)(CO)2MnCC(H)Ph. X-ray structure of phenyl(trityl)vinylidene complex (η5-C5H5)(CO)2MnCC(CPh3)Ph

Cited by 28 publications

References 24 publications

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes

Oxidative dehydrodimerization of manganese vinylidene complexes (η5‐C5R5)(CO)(L)MnCCHPh (R = Me, L = CO; R = H, L = PPh3)

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Oxidative dehydrodimerization of manganese vinylidene complexes (η⁵‐C₅R₅)(CO)(L)MnCCHPh (R = Me, L = CO; R = H, L = PPh₃)