Synthesis of monomeric niobium- and tantalum-benzyne complexes and the molecular structure of Ta(.eta.5-C5Me5)(C6H4)Me2

McLain, Stephan J.; Schrock, Richard R.; Sharp, Paul R.; Churchill, Melvyn Rowen; Youngs, Wiley J.

doi:10.1021/ja00495a067

Cited by 109 publications

(57 citation statements)

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“…Solvents were refluxed over an appropriate drying agent, distilled and degassed prior to use: [D 6 ]benzene and hexane (Na/K alloy), and toluene (Na). Starting materials Ta(η 5 ‐C 5 Me 5 )Cl 4 ,28 Ta(η 5 ‐C 5 Me 5 )Cl 2 Me 2 ,13 Ta(η 5 ‐C 5 Me 5 )Cl 2 (CH 2 CMe 3 ) 2 26a,29 and the alkylating reagents LiR (R = CH 2 SiMe 3 , CH 2 CMe 2 Ph)30 and Li(CH 2 C 6 H 5 )(tmeda)31 were prepared as previously described. Reagent grade LiMe (1.5 M in diethyl ether, Aldrich) and MgCl(CH 2 SiMe 3 ) (1 M in diethyl ether, Aldrich) were purchased from commercial sources and were used without further purification.…”

Section: Methodsmentioning

confidence: 99%

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

et al. 2006

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Alkylation of [TaCp*Cl4] (Cp* = η5‐C5Me5) with 3 equiv. of MgCl(CH2SiMe3) gives the chloridotris(trimethylsilylmethyl) complex [TaCp*Cl(CH2SiMe3)3] (1). TaCp*Cl2Me2 reacts with 2 equiv. of LiR (R = CH2Ph, CH2SiMe3) to give the mixed alkyl derivatives [TaCp*Me2R2] (R = CH2Ph, 2; CH2SiMe3, 3). The dimethyldineopentyl complex [TaCp*Me2(CH2CMe3)2] (4) was obtained by reaction of TaCp*Cl2(CH2CMe3)2 with 2 equiv. of LiMe. The treatment of a toluene solution of TaCp*Cl2Me2 with 2 equiv. of neophyllithium in a standard vacuum line gave a mixture of three compounds, [{TaCp*Me2(CH2CMe2Ph)}2(μ‐O)] (5), [TaCp*Me2(CH2CMe2–o‐C6H4‐κ2C,C)] (6) and [TaCp*Me(CH2CMe2Ph)(CH2)] (7), which were identified by NMR spectroscopy. However, when the reaction was carried out under rigorously anhydrous conditions, only complexes 6 and 7 were isolated. A chlorido(trimethylsilylmethyl)(trimethylsilylmethylidene) complex [TaCp*Cl(CH2SiMe3)(CHSiMe3)] (8) was prepared by heating 1 at 60 °C, or by leaving it at room temperature for a long time. A 3:2 (9/10) mixture of [TaCp*MeR(CHSiMe3)] (R = CH2SiMe3, 9; Me, 10) was obtained by thermal treatment of 3, which was accompanied by the evolution of CH4 and SiMe4. However, irradiation of a [D6]benzene solution of 3 with a sun lamp gave a mixture of 9 and [TaCp*(CH2SiMe3)R(CH2)] (R = Me, 11; CH2SiMe3, 12) in a 2:1:1 (9/11/12) ratio. When a [D6]benzene solution of 4 was heated at 60 °C, a mixture of the (alkyl)(neopentylidene) derivatives [TaCp*MeR(CHCMe3)] (R = Me, 13; CH2CMe3, 14) in a 4:1 (13/14) ratio was detected by NMR spectroscopy, while irradiation with a sun lamp produced a mixture ofalkylidene complexes [TaCp*(CH2CMe3)R(CH2)] (R = Me, 15; CH2CMe3, 16) in a 3:1 (15/16) ratio. On the other hand, the alkylation of TaCp*Cl2(CH2CMe3)2 with 2 equiv. of LiCH2SiMe3 gave the (alkyl)(alkylidene) complex [TaCp*(CH2CMe3)(CH2SiMe3)(CHCMe3)] (17) with the elimination of SiMe4, whereas the treatment of TaCp*Cl2(CH2SiMe3)2 with the appropriate reagent gave [TaCp*(CH2R)(CH2SiMe3)(CHR′)] (R = R′ = Ph, 18; R = CMe2Ph, R′ = SiMe3, 19) with the elimination of SiMe4 and CMe3Ph, respectively. All compounds were studied by IR and NMR spectroscopy, and the molecular structures of complexes 1, 4 and 5 were determined by X‐ray diffraction methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Methodsmentioning

confidence: 99%

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

et al. 2006

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“…Vor kurzem konnte aus [Ta(^5-C5Me5)Me3(C6H5)] die Verbindung [Ta(^5-C5Me5)Me2(C6H4)] isoliert und röntgenogra-phisch charakterisiert werden [17], die einen CeH4-Ring an nur ein Übergangsmetallatom gebunden enthält. Auch dieser Komplex wird durch thermische Reaktion gebildet.…”

Section: Diskussionunclassified

Übergangsmetallbenz - in-Komplexe. Dynamisches Verhalten von [Ta(C₆H₅)₄(C₆H₄)a(Li • OC₄H₁₀)₃] / Transition Metal Benzyne Complexes. Fluxional Behaviour of [TA(C₆H₅)₄(C₆H₄)₂(Li·OC₄H₁₀)₃]

Sarry

Schaffernicht

1981

Zeitschrift Für Naturforschung B

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“…This mechanistic hypothesis received strong support in 1979 with Schrock and co-workers' isolation of complex 8 and its structural characterization by X-ray crystallography [10]. Since then, many aryne complexes of early transition metals have been prepared, including complexes of Ti, Zr, Nb, Mo,W, Re,V, and even the actinoid elements U and Th.…”

Section: Aryne Complexes Of Early Transition Metalsmentioning

confidence: 90%

Palladium-Catalyzed Cycloaddition Reactions of Arynes

Guitián

Pérez

Peña

2005

Topics in Organometallic Chemistry

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Synthesis of monomeric niobium- and tantalum-benzyne complexes and the molecular structure of Ta(.eta.5-C5Me5)(C6H4)Me2

Cited by 109 publications

References 2 publications

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

Übergangsmetallbenz - in-Komplexe. Dynamisches Verhalten von [Ta(C₆H₅)₄(C₆H₄)a(Li • OC₄H₁₀)₃] / Transition Metal Benzyne Complexes. Fluxional Behaviour of [TA(C₆H₅)₄(C₆H₄)₂(Li·OC₄H₁₀)₃]

Palladium-Catalyzed Cycloaddition Reactions of Arynes

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Synthesis of monomeric niobium- and tantalum-benzyne complexes and the molecular structure of Ta(.eta.5-C5Me5)(C6H4)Me2

Cited by 109 publications

References 2 publications

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

Übergangsmetallbenz - in-Komplexe. Dynamisches Verhalten von [Ta(C6H5)4(C6H4)a(Li • OC4H10)3] / Transition Metal Benzyne Complexes. Fluxional Behaviour of [TA(C6H5)4(C6H4)2(Li·OC4H10)3]

Palladium-Catalyzed Cycloaddition Reactions of Arynes

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Übergangsmetallbenz - in-Komplexe. Dynamisches Verhalten von [Ta(C₆H₅)₄(C₆H₄)a(Li • OC₄H₁₀)₃] / Transition Metal Benzyne Complexes. Fluxional Behaviour of [TA(C₆H₅)₄(C₆H₄)₂(Li·OC₄H₁₀)₃]