Triisobutylaluminium-promoted formation of lanthanide hydrides

Moinet, Eric; Tardif, Olivier; Maichle‐Moessmer, Caecilia; Anwander, Reiner

doi:10.1039/d3cc01330h

Cited by 3 publications

(6 citation statements)

References 41 publications

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“…Complexes Ln[N(SiMe 3 ) 2 ] 3 (Ln = La, Pr, Nd) were prepared following standard procedures . Complexes 1 Ln were synthesized as previously reported by our group . Glassware and polymer fittings were dried prior to use for several hours at 120 °C or 80 °C, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…51 Complexes 1 Ln were synthesized as previously reported by our group. 33 Glassware and polymer fittings were dried prior to use for several hours at 120 °C or 80 °C, respectively. IR spectra were recorded on a Vertex 70 spectrometer (Bruker) in Nujol and measured in a cell equipped with CsI windows.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Complexes of the type Ln[N(SiMe 3 ) 2 ](HAliBu 3 )(AliBu 4 ) (Ln = La, Pr, Nd) (1 Ln ) recently reported by our group display the first examples of ancillary ligand-free, trivalent lanthanide isobutylaluminates. 33 Such discrete complexes feature a more intricate, but also a more realistic model system for isoprene polymerization catalysts than the frequently utilized lanthanide tetramethylaluminates, since commercially relevant mixed catalysts comprise "higher" organoaluminum compounds, such as diethylaluminum chloride, triethyl-or triisobutylaluminum (TIBA), as well as diisobutylaluminum hydride or -chloride. Early lanthanide metals were chosen due to their superior performance in industrial cis-1,4-selective diene polymerization catalysts.…”

Section: ■ Introductionmentioning

confidence: 99%

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Discrete Trivalent Lanthanide Isobutylaluminates in Isoprene Polymerization: Elucidation of Cationized Active Species

Moinet,

Tardif,

Hornberger

et al. 2023

ACS Catal.

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Triisobutylaluminum (TIBA) is a main component applied in industrial Ziegler-type mixed catalysts for conjugated diene polymerization. Despite this importance, discrete crystalline trivalent lanthanide tetraisobutylaluminates have not yet been examined in polymerization. The present study revealed that discrete complexes Ln[N(SiMe 3 ) 2 ](HAliBu 3 )(AliBu 4 ) (Ln = La, Pr, Nd, Gd) promote highly stereoselective isoprene polymerization with >99% cis selectivity. Mechanistic studies with borate cocatalysts, supported by single crystal X-ray diffraction, and NMR spectroscopy, disclose the formation of dicationic neodymium complex [Nd{N(SiMe 3 ) 2 }(PhNMe 2 ) 2 ][B-(C 6 F 5 ) 4 ] 2 from the binary system Nd[N(SiMe 3 ) 2 ](HAliBu 3 )(AliBu 4 )/[PhNMe 2 H][B(C 6 F 5 ) 4 ]. Complex [Nd{N(SiMe 3 ) 2 }-(PhNMe 2 ) 2 ][B(C 6 F 5 ) 4 ] 2 engages in single-component isoprene polymerization.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Discrete Trivalent Lanthanide Isobutylaluminates in Isoprene Polymerization: Elucidation of Cationized Active Species

Moinet,

Tardif,

Hornberger

et al. 2023

ACS Catal.

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“…34 The 1 H NMR spectrum of [La{N(SiMe 3 ) 2 }(AliBu 4 )(μ-Cl)] 2 (2 La ) at 26 °C in C 6 D 6 revealed a mixture of products, albeit 2 La proved to be pure by elemental analysis. This indicated rapid decomposition in deuterated benzene, leading to the formation of decomposition products identified as La[N(SiMe 3 ) 2 ](HAliBu 3 )(AliBu 4 ), 17 La[N(SiMe 3 ) 2 ] 3 , and isobutene by 1 H NMR resonances (see Figure S2). This decomposition scenario possibly involves the formation of LaCl 3 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Only recently, we have reported on a series of divalent, homoleptic tetraisobutylaluminates Ln(Al i Bu 4 ) 2 (Ln = Sm, Eu, Yb) and ancillary ligand-free trivalent mixed hydrido/isobutylaluminato lanthanide complexes. , However, heteroleptic rare-earth-metal complexes are usually difficult to synthesize. Major challenges include fast ligand redistribution, which are mainly driven by the tendency to form homoleptic complexes.…”

Section: Introductionmentioning

confidence: 99%

Ancillary Ligand-Free Mixed Chlorido/Isobutylaluminato Lanthanide Complexes in Isoprene Polymerization

Moinet,

Wetzel,

Tardif

et al. 2024

Organometallics

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Ternary catalyst mixtures are employed for industrial-scale rare-earth-metalpromoted diene polymerization. Thereby, the role of organoaluminum compounds in activating the rare-earth-metal component is still poorly understood. Mixed chlorido/ amido complexes [Ln{N(SiMe 3 ) 2 } 2 (μ-Cl)(THF)] 2 are selected as well-defined precursors according to the chlorination/alkylation activation sequence. The heteroleptic lanthanide tetraisobutylaluminate complexes [Ln{N(SiMe 3 ) 2 }(AliBu 4 )(μ-Cl)] 2 (Ln = La, Nd) form when [Ln{N(SiMe 3 ) 2 } 2 (μ-Cl)(THF)] 2 is treated with triisobutylaluminum. By contrast, the [La{N(SiMe 3 ) 2 } 2 (μ-Cl)(THF)] 2 /AlMe 3 reaction afforded the isolable heteroaluminate complex [La{N(SiMe 3 ) 2 }{(μ-CH 3 )(μ-N(SiMe 3 ) 2 )AlMe 2 }(μ-Cl)] 2 , highlighting the distinct reactivity of aluminum alkyls. Complex [Nd{N(SiMe 3 ) 2 }(AliBu 4 )(μ-Cl)] 2 features catalytic activity in isoprene polymerization for the fabrication of high cis-selective polyisoprene and displays single-component polymerization activity. Compounds [Ln{N(SiMe 3 ) 2 } 2 (μ-Cl)(THF)] 2 are best accessed from La[N(SiMe 3 ) 2 ] 3 /LaCl 3 (THF) mixtures since starting out from LaCl 3 (THF)/K[N(SiMe 3 ) 2 ] leads to alkali-metal contaminations as revealed by the isolation of the mixed hydrido/isobutylaluminato complex [K(iBu 3 Al-μ−H-AliBu 3 )] n , formed upon reaction with triisobutylaluminum.

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