Electrocatalytic dimerisation of non-heteroatom-substituted manganese alkynylcarbene complexesElectronic supplementary information (ESI) available: details of syntheses and spectral characterisation of the new complexes, ORTEP plot of complex 3b. See http://www.rsc.org/suppdata/cc/b3/b300623a/

Ortin, Yannick; Sournia‐Saquet, Alix; Lugan, Noël; Mathieu, René

doi:10.1039/b300623a

Cited by 24 publications

(13 citation statements)

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“…In the 13 C), complexes 3 undergo an electrocatalytic dimerization by coupling at the remote alkynyl carbon atom to afford 4 in a quantitative and stereoselective manner. 16 In view of that, we assume the formation of traces amount of 4 in the reaction conditions shown in Scheme 2 results from a dimerization of 3 triggered by the alkynyllithium reagent, acting then as reducing agent.…”

Section: Structure Of [(G 5 -Mec 5 H 4 )(Co) 2 Mn≡ctol][bph 4 ] ([2b]...mentioning

confidence: 99%

Subtle reactivity patterns of non-heteroatom-substituted manganese alkynyl carbene complexes in the presence of phosphorus probes

2005

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The non-heteroatom-substituted manganese alkynyl carbene complexes (eta5-MeC5H4)(CO)2Mn=C(R)C[triple bond]CR'(3; 3a: R = R'= Ph, 3b: R = Ph, R'= Tol, 3c: R = Tol, R'= Ph) have been synthesised in high yields upon treatment of the corresponding carbyne complexes [eta5-MeC5H4)(CO)2Mn[triple bond]CR][BPh4]([2][BPh4]) with the appropriate alkynyllithium reagents LiC[triple bond]CR' (R'= Ph, Tol). The use of tetraphenylborate as counter anion associated with the cationic carbyne complexes has been decisive. The X-ray structures of (eta5-MeC5H4)(CO)2Mn=C(Tol)C[triple bond]CPh (3c), and its precursor [(eta5-MeC5H4)(CO)2Mn=CTol][BPh4]([2b](BPh4]) are reported. The reactivity of complexes toward phosphines has been investigated. In the presence of PPh3, complexes act as a Michael acceptor to afford the zwitterionic sigma-allenylphosphonium complexes (eta5-MeC5H4)(CO)2MnC(R)=C=C(PPh3)R' (5) resulting from nucleophilic attack by the phosphine on the remote alkynyl carbon atom. Complexes 5 exhibit a dynamic process in solution, which has been rationalized in terms of a fast [NMR time-scale] rotation of the allene substituents around the allene axis; metrical features within the X-ray structure of (eta5-MeC5H4)(CO)2MnC(Ph)=C=C(PPh3)Tol (5b) support the proposal. In the presence of PMe3, complexes undergo a nucleophilic attack on the carbene carbon atom to give zwitterionic sigma-propargylphosphonium complexes (eta5-MeC5H4)(CO)2MnC(R)(PMe3)C[triple bond]CR' (6). Complexes 6 readily isomerise in solution to give the sigma-allenylphosphonium complexes (eta5-MeC5H4)(CO)2MnC(R')=C=C(PMe3)R (7) through a 1,3 shift of the [(eta5-MeC5H4)(CO)2Mn] fragment. The nucleophilic attack of PPh2Me on 3 is not selective and leads to a mixture of the sigma-propargylphosphonium complexes (eta5-MeC5H4)(CO)2MnC(R)(PPh(2)Me)C[triple bond]CR' (9) and the sigma-allenylphosphonium complexes (eta5-MeC5H4)(CO)2MnC(R)=C=C(PPh(2)Me)R' (10). Like complexes 6, complexes 9 readily isomerize to give the sigma-allenylphosphonium complexes (eta5-MeC5H4)(CO)2MnC(R')=C=C(PPh2Me)R'). Upon gentle heating, complexes 7, and mixtures of 10 and 10' cyclise to give the sigma-dihydrophospholium complexes (eta5-MeC5H4)(CO)2MnC=C(R')PMe2CH2CH(R)(8), and mixtures of complexes (eta5-MeC5H4)(CO)2MnC=C(Ph)PPh2CH2CH(Tol)(11) and (eta5-MeC5H4)(CO)2MnC=C(Tol)PMe2CH2CH(Ph)(11'), respectively. The reactions of complexes 3 with secondary phosphines HPR(1)(2)(R1= Ph, Cy) give a mixture of the eta2-allene complexes (eta5-MeC5H4)(CO)2Mn[eta2-{R(1)(2)PC(R)=C=C(R')H}](12), and the regioisomeric eta4-vinylketene complexes [eta5-MeC5H4)(CO)Mn[eta4-{R(1)(2)PC(R)=CHC(R')=C=O}](13) and (eta5-MeC5H4)(CO)Mn[eta4-{R(1)(2)PC(R')=CHC(R)=C=O}](13'). The solid-state structure of (eta5-MeC5H4)(CO)2Mn[eta2-{Ph2PC(Ph)=C=C(Tol)H}](12b) and (eta5-MeC5H4)(CO)Mn[eta4-{Cy2PC(Ph)=CHC(Ph)=C=O}](13d) are reported. Finally, a mechanism that may account for the formation of the species 12, 13, and 13' is proposed.

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Section: Structure Of [(G 5 -Mec 5 H 4 )(Co) 2 Mn≡ctol][bph 4 ] ([2b]...mentioning

confidence: 99%

Subtle reactivity patterns of non-heteroatom-substituted manganese alkynyl carbene complexes in the presence of phosphorus probes

2005

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“…To date, manganese carbene complexes derived from MMT have found much less applications to organic synthesis than their group 6 analogues, certainly because of the reduced electrophilicity of their carbenic carbon atom inherent to the relatively poor electron-withdrawing ability of the Cp′(CO) 2 Mn fragment . As far as manganese carbene chemistry is concerned, the observations summarized in Scheme are quite gratifying for two reasons.…”

Section: Introductionmentioning

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Directed Formation of Allene Complexes upon Reaction of Non-heteroatom-Substituted Manganese Alkynyl Carbene Complexes with Nucleophiles

et al. 2008

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The non-heteroatom-substituted alkynyl carbene Cp′(CO) 2 MndC(Tol)CtCPh (1, Cp′ ≡ (η 5 -MeC 5 H 4 )) is first shown to react at low temperature with lithium diorganophosphide LiPR 2 (R ) Ph, Cy) to form an anionic species. Subsequent treatment with CF 3 SO 3 H affords the η 4 -vinylketene complex Cp′(CO) 2 Mn[η 4 -{R 2 P(Ph)CdCHC(Tol)dCdO}] (2; 2a: R ) Ph (70% yield), 2b: R ) Cy (55% yield)) as the major compound, along with trace amounts of the η 2 -allene complex syn-Cp′(CO) 2 Mn[η 2 -{Ph 2 P(Tol)-CdCdC(Ph)H}] (syn-3a) for R ) Ph, or along with the η 2 -allene complex Cp′(CO) 2 Mn[η 2 -{H(Tol)-CdCdC(Ph)PCy 2 }] (4b, 26% yield, 1:2 mixture of syn/anti isomers) for R ) Cy. On the other hand, subsequent treatment with NH 4 Cl aq affords only η 2 -allene complexes, obtained either as a ca. 1:9 mixture of syn-3a and Cp′(CO) 2 Mn[η 2 -{H(Tol)CdCdC(Ph)PPh 2 }] (4a) (75% yield) for R ) Ph or as a 1:2 mixture of syn-and anti-4b for R ) Cy (74% yield). Combined NMR and single-crystal X-ray diffraction studies (for 2a, anti-4b, and syn-4b) revealed that both type 2 and type 4 species result from a nucleophilic attack of the diorganophosphide onto the remote alkynyl carbon atom in 1 (C γ ), whereas type 3 species results from a nucleophilic attack of the carbene carbon atom (C R ). Complexes 3a and 4a,b are prone to undergo a thermal rearrangement to give the η 1 -phosphinoallene complexes Cp′(CO) 2 Mn[η 1 -{Ph 2 P(Tol)CdCdC(Ph)H}] (5a) and Cp′(CO) 2 Mn[η 1 -{R 2 P(Ph)CdCdC(Tol)H}] (6; 6a: R ) Ph, 6b: R ) Cy), respectively. Reaction of 1 with p-toluenethiol in the presence of NEt 3 (20%) affords a 1.8:1 mixture of Cp′(CO) 2 Mn[η 2 -{TolS(Tol)CdCdC(Ph)H}] (syn-11), resulting from a nucleophilic attack at C R in 1, and Cp′(CO) 2 Mn[η 2 -{H(Tol)CdCdC(Ph)STol}] (12), resulting from a nucleophilic attack at C γ , whereas treatment of 1 with lithium p-toluenethiolate at -80 °C followed by protonation with NH 4 Cl aq gave the same syn-11 and 12 complexes now in a 1:2.3 ratio. Finally, 1 was found to react with cyclohexanone lithium enolate to afford, upon protonation, the η 2 -allene complex Cp′(CO) 2 Mn[η 2 -{H(Tol)CdCdC(Ph)CH(CH 2 ) 4 C(O)}] (syn-13), resulting from a nucleophilic attack at C γ in 1. The solidstate structures of syn-11 and syn-13 are also reported.

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“…The classical DCD model is much less appropriate here. Interestingly, these bonding descriptions can be related to chemical reactivity as the alkyne ligand in half-sandwich Cp(CO) 2 Mn-(η 2 -2e-alkyne) complexes is easily displaced, by acetonitrile for instance, 24 while L n Nb(η 2 -4-e-alkyne) complexes are inert to substitution. 6,25 This is correlated with lower bond ellipticity at the Nb⋯C bcp's which should indicate greater contribution to This journal is © The Royal Society of Chemistry 2012 the bonding perpendicularly to the NbCC plane.…”

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A comparative study of the topology of the experimental electron density within 2 and 4e− donor alkyne complexes

et al. 2012

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A comparison of the topology of the experimental electron density, as revealed by high resolution X-ray diffraction, is provided for two prototypal transition metal alkyne complexes where the alkyne formally behaves as a 2 or 4e(-) donor. A higher value of the electron density ρ(r)(bcp) at the M(T)···C bond critical point (bcp), a lower value of ρ(r)(bcp) at the coordinated C≡C bcp, outwardly bent MC bond paths and a close to zero ellipticity for the C[triple bond, length as m-dash]C bond constitute the topological signature of a 4e(-) donor alkyne ligand.

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Electrocatalytic dimerisation of non-heteroatom-substituted manganese alkynylcarbene complexesElectronic supplementary information (ESI) available: details of syntheses and spectral characterisation of the new complexes, ORTEP plot of complex 3b. See http://www.rsc.org/suppdata/cc/b3/b300623a/

Cited by 24 publications

References 10 publications

Subtle reactivity patterns of non-heteroatom-substituted manganese alkynyl carbene complexes in the presence of phosphorus probes

Subtle reactivity patterns of non-heteroatom-substituted manganese alkynyl carbene complexes in the presence of phosphorus probes

Directed Formation of Allene Complexes upon Reaction of Non-heteroatom-Substituted Manganese Alkynyl Carbene Complexes with Nucleophiles

A comparative study of the topology of the experimental electron density within 2 and 4e− donor alkyne complexes

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