Multiple metal-carbon bonds. 39. Preparation of molybdenum and tungsten neopentylidyne complexes of the type M(CCMe3)(O2CR)3, their reactions with acetylenes, and the x-ray structure of the .eta.3-cyclopropenyl complex W[C3(CMe3)Et2](O2CCH3)3

Schrock, Richard R.; Murdzek, John S.; Freudenberger, John H.; Ziller, J.W.

doi:10.1021/om00132a005

Cited by 38 publications

(32 citation statements)

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“…Neither the tris(neopentyl) complex 8 nor complexes bearing sterically hindered -NR 2 , -SR, or carboxylate groups as ancillary ligands give any sustained metathesis. [32,34,41,42] In contrast, the use of bulky phenolates leads to active catalysts, which may be unsurprising in view of Mortreuxs results. Complex 1 e, for example, with 2,6diisopropylphenolate ligands, even allowed the corresponding metallacyclobutadiene 12 e to be isolated from reactions with excess 3-hexyne.…”

Section: Lessons From the Organometallic Chemistry Of Schrock-type Tumentioning

confidence: 99%

Alkyne Metathesis on the Rise

2013

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The early years of alkyne metathesis were marked by a somewhat ironic state of affairs: the proposed mechanism was swiftly validated and more than one effective catalyst became available shortly after the discovery of this transformation; surprisingly, however, the impact on synthesis remained very limited for a long period of time. Recent advances, however, suggest that this situation is about to change: the remarkable activity, functional-group tolerance, and reliability of the latest generation of catalysts open the door for highly advanced applications. The resulting (cyclo)alkynes are amenable to numerous postmetathetic transformations, which diversify the product portfolio and bring many different structural motifs into reach. Since the catalysts have also evolved from the glovebox to the benchtop, there should be little barrier left for a wider use of this reaction in organic synthesis.

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Section: Lessons From the Organometallic Chemistry Of Schrock-type Tumentioning

confidence: 99%

Alkyne Metathesis on the Rise

2013

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“…Metallacyclobutadienes were early identified as intermediates in alkyne metathesis and isolated from reaction mixtures of catalyst and substrate. [2e], [4a], , Recently, a molybdatetrahedrane complex was also detected as a reaction intermediate in a Mo alkylidyne complex bearing a siloxide ligand . Similar to some previously published metallacyclobutadienes, W7 does not perform a full metathesis cycle at room temperature but stops at the stage of the metallacyclobutadiene.…”

Section: Resultsmentioning

confidence: 99%

Cationic Tungsten Alkylidyne N‐Heterocyclic Carbene Complexes: Synthesis and Reactivity in Alkyne Metathesis

et al. 2020

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The first cationic and neutral tungsten alkylidyne N‐heterocyclic carbene (NHC) complexes bearing one triflate ligand were synthesized and tested for their reactivity in alkyne metathesis. Both types of tungsten alkylidyne complexes display a higher productivity in alkyne metathesis than the analogous neutral tungsten alkylidyne NHC trisalkoxide complexes. Reaction of W(≡CC6H4OMe)(1,3‐bis(1‐hydroxy‐1,1‐trifluoromethylethyl)‐imidazol‐2‐ylidene)Cl (W18) with AgB(ArF)4 (ArF = 3,5‐bis(trifluoromethyl)phenyl) resulted in the unexpected formation of, to the best of our knowledge, the first cationic ditungstatetrahedrane W2(1,3‐bis(1‐hydroxy‐1,1‐trifluoromethyl‐ethyl)‐imidazol‐2‐ylidene)2(MeCN)(µ‐((Ar)CC(Ar)))+ (B(ArF)4)– (W19, Ar = C6H4OMe), which suggests bimolecular decomposition as a possible decomposition pathway of cationic tungsten alkylidyne NHC complexes. Reaction of the cationic tungsten alkylidyne NHC complex W(≡CC6H4OMe)(1,3‐diisopropylimidazol‐2‐ylidene)(OC(CF3)2Me)2(NCtBu)+ (B(ArF)4)– (W7) with 1‐phenyl‐1‐propyne allowed for the isolation of a cationic tungstacyclobutadiene W(C3(Ph)(Me)(C6H4OMe))(1,3‐diisopropylimidazol‐2‐ylidene)(OC(CF3)2Me)2(NCtBu)+ (B(ArF)4)– (W20). Its formation strongly supports a cationic active species in the alkyne metathesis with tungsten alkylidyne NHC complexes.

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“…[26] Other high-valent carbyne complexes that have been reported to reactw ith alkynes to give cyclopentadienyl complexes include [Mo( CCMe 3 )(O 2 CCF 3 ) 3 (dme)]a nd [W( CCMe 3 )(O 2 CCMe 3 ) 3 (dme)]. [63] Formation of cyclopentadienyl complexes has also been observedi nr eactions of alkynesw ith low-valent metallacyclobutadienes.F or example, the iridacyclobutadiene 35 reactedw ith an excess amount of phenylacetylene in toluene heatedu nder reflux conditions to give the cyclopentadienyl complex 133 (Scheme 38). The same compound was formed when [IrCl(CS)(PPh 3 ) 2 ]( 31 b)w as heated with an excess amount of phenylacetylene in tolueneh eated under reflux conditions.…”

Section: Scheme33 Synthesis Of the Iridabenzene 123mentioning

confidence: 99%

Chemistry of Metallacyclobutadienes

Cui

Lin

Jia

2018

Chemistry An Asian Journal

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Metallacyclobutadienes are analogues of cyclobutadienes in which one of the cyclobutadiene CR groups has been formally replaced by a transition-metal fragment. These metallacycles are interesting because they can play an important role in catalysis and can serve as starting materials for the syntheses of organometallic compounds such as metallabenzene, η -cyclopentadienyl, and η -cyclopropenyl complexes. Unlike cyclobutadienes, metallacyclobutadienes can be significantly more stable. A number of metallacyclobutadienes have now been isolated and thoroughly characterized, especially for those that contain transition metals of groups 5-9. Their properties have also been actively investigated. This article highlights the chemistry of metallacyclobutadienes with reference to their syntheses, reactivity, and structural properties.

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Multiple metal-carbon bonds. 39. Preparation of molybdenum and tungsten neopentylidyne complexes of the type M(CCMe3)(O2CR)3, their reactions with acetylenes, and the x-ray structure of the .eta.3-cyclopropenyl complex W[C3(CMe3)Et2](O2CCH3)3

Cited by 38 publications

References 1 publication

Alkyne Metathesis on the Rise

Alkyne Metathesis on the Rise

Cationic Tungsten Alkylidyne N‐Heterocyclic Carbene Complexes: Synthesis and Reactivity in Alkyne Metathesis

Chemistry of Metallacyclobutadienes

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