Eine Seltenerdmetallvariante des Tebbe‐Reagens

Litlabø, Rannveig; Zimmermann, Melanie; Saliu, Kuburat; Takats, Josef; Törnroos, Karl W.; Anwander, Reiner

doi:10.1002/ange.200803856

Cited by 34 publications

(24 citation statements)

References 50 publications

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“…[18] The anionic methyl groups exhibit longer bond lengths of . [19] In contrast to the end-on aluminate coordination to the samarium atom in the divalent samarium compounds discussed above, the Y (1) . [16] We expected that addition of the same ligand to a solution of [YA C H T U N G T R E N N U N G (AlMe 4 ) 3 ] in toluene would result solely in C À H activation because an equivalent reduction of yttriumA C H T U N G T R E N N U N G (III) seemed unlikely.…”

Section: Resultsmentioning

confidence: 93%

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

Bojer

Venugopal

Mix

et al. 2011

Chemistry A European J

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The reaction of 1,3,5-triisopropyl-1,3,5-triazacyclohexane (TiPTAC) with [Y(AlMe(4))(3)] resulted in the formation of [(TiPTAC)Y(Me(3)AlCH(2)AlMe(3))(μ-MeAlMe(3))] by C-H activation and methane extrusion. In contrast, the presence of bulkier cyclohexyl groups on the nitrogen atoms in 1,3,5-tricyclohexyl-1,3,5-triazacyclohexane (TCyTAC) led to the formation of the cationic dimethyl complex [(TCyTAC)(2)YMe(2)][AlMe(4)]. The investigations reveal a dependency of the reaction mechanism on the steric bulk of the N-alkyl entity and the solvent employed. In toluene C-H activation was observed in reactions of [Y(AlMe(4))(3)] with 1,3,5-trimethyl-1,3,5-triazacyclohexane (TMTAC) and TiPTAC. In THF molecular dimethyl cations, such as [(TCyTAC)(2)YMe(2)][AlMe(4)], [(TMTAC)(2)YMe(2)][AlMe(4)] and [(TiPTAC)(2)YMe(2)][AlMe(4)], could be synthesised by addition of the triazacyclohexane at a later stage. The THF-solvated complex [YMe(2)(thf)(5)][AlMe(4)] could be isolated and represents an intermediate in these reactions. It shows that cationic methyl complexes of the rare-earth metals can be formed by donor-induced cleavage of the rare-earth-metal tetramethylaluminates. The compounds were characterised by single-crystal X-ray diffraction or multinuclear and variable-temperature NMR spectroscopy, as well as elemental analyses. Variable-temperature NMR spectroscopy illustrates the methyl group exchange processes between the cations and anions in solution.

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Section: Resultsmentioning

confidence: 93%

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

Bojer

Venugopal

Mix

et al. 2011

Chemistry A European J

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“…[9b, d, [15][16][17] Interestingly, when three equivalents of AlMe 3 were used to react with complexes 1, colorless heterobimetallic bis(tetramethylaluminate) complexes [(NCN)LnA C H T U N G T R E N N U N G (AlMe 4 ) 2 ] (Ln= Sc (3 a), Lu (3 b)) were obtained in good yields (Scheme 1).…”

Section: Resultsmentioning

confidence: 98%

“…[19] Whereas the average AlÀCA C H T U N G T R E N N U N G (m 2 -CH 3 ) bond is significantly longer than the average AlÀC(terminal-CH 3 ) bond (2.044 vs. 1.950 for 3 a; 2.050 vs. 1.950 for 3 b; see Table 2) in the solid state, only one signal was observed in the 1 H NMR spectrum in C 6 D 6 , probably because of the rapid exchange between the bridging CH 3 and the terminal CH 3 in solvent at ambient temperature. [15,19] Noticeably, treatment of 2 b with six equivalents of AlMe 3 in toluene at ambient temperature produced complex 3 b in 61 % yield. But 2 a was inert toward AlMe 3 under the same conditions.…”

Section: Resultsmentioning

confidence: 98%

“…In addition, a few discrete rare-earth-metal methylidene complexes that bear a M-CH 2 -M motif have also been reported. For example, Anwander and co-workers synthesized solvated Cl-bridging methylidene [Cp* 3 Y 3 A C H T U N G T R E N N U N G (m 2 -Cl) 3 )H = hydrotris(pyrazolyl)borate), [15] and [(Tp tBu,Me…”

Section: -Css'}a C H T U N G T R E N N U N G (M-i)a C H T U N G T Rmentioning

confidence: 99%

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Syntheses, Structures, and Reactivities of Homometallic Rare‐Earth‐Metal Multimethyl Methylidene and Oxo Complexes

Hong

Zhang

et al. 2011

Chemistry A European J

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Unsolvated, trinuclear, homometallic, rare-earth-metal multimethyl methylidene complexes [{(NCN)Ln(μ(2)-CH(3))}(3)(μ(3)-CH(3))(μ(3)-CH(2))] (NCN = L = [PhC{NC(6)H(4)(iPr-2,6)(2)}(2)](-); Ln = Sc (2a), Lu (2b)) have been synthesized by treatment of [(L)Ln{CH(2)C(6)H(4)N(CH(3))(2)-o}(2)] (Ln = Sc (1a), Lu (1b)) with two equivalents of AlMe(3) in toluene at ambient temperature in good yields. Treatment of 1 with three equivalents of AlMe(3) gives the heterometallic trinuclear complexes [(L)Ln(AlMe(4))(2)] (Ln = Sc (3a), Lu (3b)) in good yields. Interestingly, 2 can also be generated by recrystallization of 3 in THF/toluene, thereby indicating that the THF molecule can also induce C-H bond activation of 2. Reaction of 2 with one equivalent of ketones affords the trinuclear homometallic oxo-trimethyl complexes [{(L)Ln(μ(2) -CH(3))}(3) (μ(3)-CH(3))(μ(3)-O)] (Ln = Sc(4a), Lu(4b)) in high yields. Complex 4b reacts with one equivalent of cyclohexanone to give the methyl abstraction product [{(L)Lu(μ(2) -CH(3) )}(3) (μ(3) -OC(6)H(9))(μ(3)-O)] (5b), whereas reaction of 4b with acetophenone forms the insertion product [{(L)Lu(μ(2)-CH(3))}(3){μ(3)-OCPh(CH(3))(2)}(μ(3)-O)] (6b). Complex 4a is inert to ketone under the same conditions. All these new complexes have been characterized by elemental analysis, NMR spectroscopy, and confirmed by X-ray diffraction determination.

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“…[30] Für das Element Cer wurde bei der Berechnung der Schwingungsfrequenzen für das doppelt-gebundene CeCH 2 + -Ion eine imaginäre Frequenz [30] so wie es in den Verbindungen 6, 8 und 10 beobachtet wurde. [18,20,22] Diese Ergebnisse sind im Einklang mit früheren DFT-und Matrix-IR-Studien an Uran-und Thoriummethylidenkomplexen, bei denen ebenfalls eine agostische Wechselwirkung zwischen dem Metallzentrum und einem Wasserstoffatom der Methylidengruppe nachgewiesen werden konnte. [32][33] …”

Section: Dft-rechnungenunclassified

Methylidenkomplexe der Seltenerdmetalle

Kratsch

Roesky

2013

Angewandte Chemie

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Übergangsmetallcarbene sind bereits seit 50 Jahren bekannt und haben eine breite Anwendung als Reagentien und Katalysatoren in der organischen Synthese gefunden. Die Carbenchemie der Seltenerdmetalle ist dagegen noch recht wenig untersucht und erst in den letzten Jahren in den Fokus der Forschung gerückt. Vor allem Seltenerdmetallalkylidenverbindungen, insbesondere Methylidenkomplexe, sind eine aufstrebende Verbindungsklasse mit einem hohen Potential für die Organometallchemie und möglicherweise künftig für die organische Synthese.

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Eine Seltenerdmetallvariante des Tebbe‐Reagens

Cited by 34 publications

References 50 publications

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

Syntheses, Structures, and Reactivities of Homometallic Rare‐Earth‐Metal Multimethyl Methylidene and Oxo Complexes

Methylidenkomplexe der Seltenerdmetalle

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Eine Seltenerdmetallvariante des Tebbe‐Reagens

Cited by 34 publications

References 50 publications

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe4)3] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe4)3] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

Syntheses, Structures, and Reactivities of Homometallic Rare‐Earth‐Metal Multimethyl Methylidene and Oxo Complexes

Methylidenkomplexe der Seltenerdmetalle

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Product

Resources

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CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects