Yttrium half-sandwich complexes bearing the 2-(N,N-dimethylamino)ethyl-tetramethylcyclopentadienyl ligand

Jende, Lars N.; Maichle‐Mößmer, Cäcilia; Schädle, Christoph

doi:10.1016/j.jorganchem.2013.05.002

Cited by 12 publications

(10 citation statements)

References 43 publications

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“…After evaporation of the volatiles, a clean spectrum of the reaction products was obtained, suggesting the formation of two different species (Figure b). A closer examination of the obtained data unambiguously verified one of the species as the yttrium half-sandwich bis(tetramethylaluminate) complex [Cp NMe2AlMe3 Y(AlMe 4 ) 2 ] ( 4 ) reported recently (Figure c). , …”

Section: Resultsmentioning

confidence: 99%

“…The addition of an excess of Al i Bu 3 led to mainly cis-1,4-regulated polyisoprene, while the use of AlMe 3 produced polymers with dominant trans-1,4-microstructure. NMR spectroscopic studies of the mixture Cp NMe2 Y(η 3 -C 3 H 5 ) 2 /AlMe 3 revealed rapid [allyl] → [aluminate] exchange (allyl/methyl scrambling) with loss of the constrained geometry conformation involving the formation of complexes such as Cp NMe2AlMe3 Y(AlMe 4 ) 2 . In accordance with the NMR study, the catalyst systems Cp NMe2 Y(η 3 -C 3 H 5 ) 2 /[PhNMe 2 H][B(C 6 F 5 ) 4 ]/AlMe 3 and Cp NMe2AlMe3 Y(AlMe 4 ) 2 /[PhNMe 2 H][B(C 6 F 5 ) 4 ] showed similar performance.…”

Section: Discussionmentioning

confidence: 99%

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Rare-Earth-Metal Allyl Complexes Supported by the [2-(N,N-Dimethylamino)ethyl]tetramethylcyclopentadienyl Ligand: Structural Characterization, Reactivity, and Isoprene Polymerization

et al. 2014

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Rare-earth-metal half-sandwich allyl complexes bearing an amino-functionalized cyclopentadienyl ligand (Cp NMe2 = 1-[2-(N,N-dimethylamino)ethyl]-2,3,4,5-tetramethylcyclopentadienyl) were synthesized in a two-step saltmetathesis reaction. Treatment of LnCl 3 (THF) x with LiCp NMe2 , followed by an in situ reaction with the Grignard reagent C 3 H 5 MgCl, generated the bis(allyl) half-sandwich complexes Cp NMe2 Ln(η 3 -C 3 H 5 ) 2 only for the smaller rare-earth metals (Ln = Y, Ho, Lu) in good yields (82−88%). In case of the larger neodymium, the dimeric mono(allyl) chlorido half-sandwich complex [Cp NMe2

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Rare-Earth-Metal Allyl Complexes Supported by the [2-(N,N-Dimethylamino)ethyl]tetramethylcyclopentadienyl Ligand: Structural Characterization, Reactivity, and Isoprene Polymerization

et al. 2014

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“…Apart from their inherent dual reactivity towards homoleptic complexes [Ln(AlMe 4 ) 3 ], which contained the distinct Lewis acidic metal centers Ln III and Al III , the performance of the resulting half‐sandwich complexes towards 1,3‐diene polymerization has also been investigated. Preliminary work on alternative synthesis procedures involved the formation of [{(Cp NMe2 )YMe 2 (MeLi)} 2 ], which features a rare example of a structurally authenticated half‐sandwich dimethyl complex (Scheme , G ) 16…”

Section: Introductionmentioning

confidence: 99%

Rare‐Earth‐Metal Alkylaluminates Supported by N‐Donor‐Functionalized Cyclopentadienyl Ligands: CH Bond Activation and Performance in Isoprene Polymerization

Jende¹,

Maichle‐Mößmer²,

Anwander³

2013

Chemistry A European J

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Homoleptic tetramethylaluminate complexes [Ln(AlMe4)3] (Ln=La, Nd, Y) reacted with HCp(NMe2) (Cp(NMe2) =1-[2-(N,N-dimethylamino)-ethyl]-2,3,4,5-tetramethyl-cyclopentadienyl) in pentane at -35 °C to yield half-sandwich rare-earth-metal complexes, [{C5 Me4CH2CH2NMe2 (AlMe3)}Ln(AlMe4)2]. Removal of the N-donor-coordinated trimethylaluminum group through donor displacement by using an equimolar amount of Et2O at ambient temperature only generated the methylene-bridged complexes [{C5Me4CH2CH2NMe(μ-CH2)AlMe3}Ln(AlMe4)] with the larger rare-earth-metal ions lanthanum and neodymium. X-ray diffraction analysis revealed the formation of isostructural complexes and the C-H bond activation of one aminomethyl group. The formation of Ln(μ-CH2)Al moieties was further corroborated by (13)C and (1)H-(13)C HSQC NMR spectroscopy. In the case of the largest metal center, lanthanum, this C-H bond activation could be suppressed at -35 °C, thereby leading to the isolation of [(Cp(NMe2))La(AlMe4)2], which contains an intramolecularly coordinated amino group. The protonolysis reaction of [Ln(AlMe4)3] (Ln=La, Nd) with the anilinyl-substituted cyclopentadiene HCp(AMe2) (Cp(AMe2) =1-[1-(N,N-dimethylanilinyl)]-2,3,4,5-tetramethylcyclopentadienyl) at -35 °C generated the half-sandwich complexes [(Cp(AMe2))Ln(AlMe4)2]. Heating these complexes at 75 °C resulted in the C-H bond activation of one of the anilinium methyl groups and the formation of [{C5Me4C6H4NMe(μ-CH2)AlMe3}Ln(AlMe4)] through the elimination of methane. In contrast, the smaller yttrium metal center already gave the aminomethyl-activated complex at -35 °C, which is isostructural to those of lanthanum and neodymium. The performance of complexes [{C5Me4CH2CH2NMe(μ-CH2 )AlMe3}-Ln(AlMe4)], [(Cp(AMe2))Ln(AlMe4)2], and [{C5Me4C6H4NMe(μ-CH2)AlMe3}Ln(AlMe4)] in the polymerization of isoprene was investigated upon activation with [Ph3C][B(C6F5)4], [PhNMe2 H][B(C6F5)4], and B(C6F5)3. The highest stereoselectivities were observed with the lanthanum-based pre-catalysts, thereby producing polyisoprene with trans-1,4 contents of up to 95.6 %. Narrow molecular-weight distributions (Mw/Mn <1.1) and complete consumption of the monomer suggested a living-polymerization mechanism.

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“…Formation of N-H bonds and silylamido ligand degradation were also observed for Lewis acidic Ln(III) bis(trimethylsilyl)amide complexes in reactions with alcohols (Covert et al, 1991;Bradley et al, 1992;Herrmann et al, 1994). Also, activation of Si-H bonds in lanthanide bis(dimethylsilyl)amide complexes is known in literature (Jende et al, 2013 and references therein). Cleavage of the N-Si bond of the silylamido ligand was observed when AlCl 3 was reacted with the amine HN(SiMe 3 ) 2 as well as in the salt metathesis of AlCl 3 and LiN(SiHMe 2 ) 2 , yielding the same -N(H)SiR 3 bridge.…”

Section: Resultsmentioning

confidence: 99%

Unusual reaction pathways of gallium(III) silylamide complexes

Koenig

Gerstberger

Schaedle

et al. 2013

Main Group Metal Chemistry

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The synthesis of homoleptic gallium(III) bis(dimethylsilyl)amide Ga[N(SiHMe 2 ) 2 ] 3 was attempted via different pathways. A transsilylamination protocol using Ga[N(SiMe 3 ) 2 ] 3 and HN(SiHMe 2 ) 2 was unsuccessfully applied. An unexpected side product, MeGa[N(SiMe 3 ) SiMe 2 N(SiMe 3 ) 2 ] 2 , could be obtained from the synthesis of homoleptic gallium(III) bis(trimethylsilyl)amide via GaCl 3 and LiN(SiMe 3 ) 2 . Alkane elimination from Me 3 Ga or Et 3 Ga and HN(SiHMe 2 ) 2 did not lead to the isolation of Ga[N(SiHMe 2 ) 2 ] 3 either. When a salt metathesis route was conducted, reacting GaCl 3 with LiN(SiHMe 2 ) 2 , the silylamido-bridged dimeric hydride complex {H 2 Ga[μ-N(SiHMe 2 ) 2 ]} 2 was obtained. Its further reaction with N,N,N′,N′-tetramethylethylendiamine (tmeda) gave the dinuclear, tmeda-bridged {[H 2 GaN(SiHMe 2 ) 2 ] 2 (μ-tmeda)}.

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Yttrium half-sandwich complexes bearing the 2-(N,N-dimethylamino)ethyl-tetramethylcyclopentadienyl ligand

Cited by 12 publications

References 43 publications

Rare-Earth-Metal Allyl Complexes Supported by the [2-(N,N-Dimethylamino)ethyl]tetramethylcyclopentadienyl Ligand: Structural Characterization, Reactivity, and Isoprene Polymerization

Rare-Earth-Metal Allyl Complexes Supported by the [2-(N,N-Dimethylamino)ethyl]tetramethylcyclopentadienyl Ligand: Structural Characterization, Reactivity, and Isoprene Polymerization

Rare‐Earth‐Metal Alkylaluminates Supported by N‐Donor‐Functionalized Cyclopentadienyl Ligands: CH Bond Activation and Performance in Isoprene Polymerization

Unusual reaction pathways of gallium(III) silylamide complexes

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