856321-17-0

Upstream product

• 109-99-9 tetrahydrofuran 
• 75-24-1 trimethylaluminum 

Relevant academic research and scientific papers

The Alkylaluminate/Gallate Trap: Metalation of Benzene by Heterobimetallic Yttrocene Complexes [Cp*2Y(MMe3R)] (M = Al, Ga)

Yttrocene derivatives [Cp*2Y(MMe4)] (Cp? = C5Me5; M = Al, Ga) and Cp*2Y[Me3Al{B(NDippCH)2}] (Dipp = C6H3iPr2-2,6) deprotonate benzene at elevated temperatures via the release of methane. The formation of [Cp*2Y(Me2MPh2)] (M = Al, Ga), Cp*2Y(MPh4) (M = Al, Ga), Cp*2Y[Me2AlPh{B(NDippCH)2}], and Cp*2Y[AlPh3{B(NDippCH)2}] can be controlled via the temperature applied. The activation temperature and formation of the coordinatively unsaturated reactive [Cp*2YMe] strongly depend on the coordination strength of the displaceable Lewis acids [AlMe3]2, GaMe3, and [Me2Al{B(NDippCH)2}]2. Hence, [Cp*2Y(AlMe4)] requires temperatures above 100 °C to metalate benzene, while Cp*2Y[AlMe3{B(NDippCH)2}] undergoes C-H-bond activation even at ambient temperatures. A kinetic deuterium isotope effect was observed for the reactions in C6D6 solutions. Distinct differences in the stabilities of the bulky Group 13 anions ([Me2MPh2]-, [MPh4]-, [Me3Al{B(NDippCH)2}]-, [Me2AlPh{B(NDippCH)2}]-, and [AlPh3{B(NDippCH)2}]-) are assessed by detailed studies of the coordination chemistry with tetrahydrofuran (THF) and by variable-temperature 1H NMR spectroscopy. Thus, increased steric bulk or a reduced Lewis acidity of the Group 13 metal center promote temperature-sensitive dissociation of trivalent Group 13 alkyl entities. Consequently, compound Cp*2Y[AlPh3{B(NDippCH)2}] was found to engage in a dissociation equilibrium with [Cp*2YPh] and AlPh2{B(NDippCH)2} in a C6D6 solution at ambient temperature. The reaction of Cp*2Y[AlPh3{B(NDippCH)2}] with THF results in the concomitant formation of monometallic Cp*2YPh(THF) and the solvent-separated ion pair [Cp*2Y(THF)2][AlPh3{B(NDippCH)2}].

Structure - Reactivity relationships in rare-earth metal carboxylate-based binary Ziegler-type catalysts

The organoaluminum-mediated alkylation of tailor-made rare-earth metal carboxylate complexes was studied, and implications of the degree of Ln alkylation and organoaluminum-chloride-mediated cation formation for 1,3-diene polymerization were investigated. Highly substituted rare-earth metal benzoate complexes {Ln(O2CC6H2Me3-2,4,6) 3}n (Ln = Y, La, Nd), {Ln(O2CC 6H2iPr3-2,4,6)3}n (Ln = Y, La, Nd, Gd, Lu), {Ln(O2CC6H2tBu 3-2,4,6)3(THF)}n (Ln = Y, La), {Ln(O 2CC6H3Ph2-2,6)3(THF)}n (Ln = Y, La), and {Ln(O2CC6H3Mes 2-2,6)3(THF)}n (Ln = Y, La) were obtained quantitatively according to the silylamide route from Ln[N(SiMe 3)2]3 and alkyl(aryl)-substituted benzoic acids. Such oligomeric carboxylate complexes are insoluble in aliphatic and aromatic solvents, but could be crystallized from donor solvents such as THF, DMSO, and pyridine. X-ray crystallographic analyses indicated the formation of monomeric [Nd(O2CC6H2Me3-2,4,6) 3(DMSO)3] and dimeric [La(O2CC 6H2Me3-2,4,6)2(μ-O 2CC6H2Me3-2,4,6)-(DMSO) 2]2 depending on the metal ion size. Depending on the steric demand of the benzoate ligands, mono- and bis(tetraalkylaluminate) complexes [Me2Al(O2CC6H2/Pr 3-2,4,6)2]2Ln[(M-Me)2AlMe 2] and {Ln(O2CC6H2tBu 3-2,4,6)[(M-Me)2AlMe2]2} 2, respectively, could be identified as major product components from the reaction with excess AlR3 (R = Me, Et), by means of 1H NMR spectroscopy and X-ray structure analysis. When activated with Et2AlCl, the resulting binary Ziegler-type catalysts efficiently polymerized isoprene (>99% cis-1,4), the polymerization performance depending on the metal center (Nd > Gd > La) and the degree of alkylation ( Ln(AlMe4)2 > Ln(AlMe 4) )- Equimolar reaction of [Me2Al(O 2-CC6H2iPr3-2,4,6)2] 2Ln[(w-Me)2AlMe2] with R2AlCl (R = Me,. Et) quantitatively produced [Me2Al(O2-CC 6H2iPr3-2,4,6)]2, proposing Me2LnCl as the polymerization-initiating species. Homoleptic Ln(AlMe4)3 was spotted as a crucial reaction intermediate and was used for the high-yield synthesis of the various alkylated carboxylate complexes according to a novel tetraalkylaluminate route.

A lewis base promoted alkyl/alkoxide ligand redistribution: Reaction of [Me2Al(μ-OCPh3)]2 with THF

The reaction of [Me2Al(μ-OEPh3)]2 with pyridine yields the expected acid-base complexes AlMe2(OEPh3)(py) [E = C (1) and Si (2)]. In contrast, the reaction with THF yields AlMe-(OEPh3)2(THF) [E = C (5) and Si (6)], although the dimethyl compounds, AlMe2(OEPh3)-(THF) [E = C (3) and Si (4)], are observed in THF-d8 solution. The reaction of [Me2Al(μOCPh3)]2 with THF was followed by 1H NMR and found to occur by a two-step process. First, the Al2O2 core of [Me2Al(μ-OEPh3)]2 is cleaved by THF to form compound 3. Second, two molecules of AlMe2(OCPh3)(THF) react with each other, with prior dissociation of THF from at least one complex, resulting in the ligand redistribution and the formation of 5 and AlMe3-(THF). The conversion of [Me2Al(μ-OCPh3)]2 into compound 3 is exothermic, and the subsequent formation of 5 and AlMe3(THF) is endothermic. The rate equations for the formation of 3 and its conversion to 5 have been determined. The observation of both alkoxide cleavage and alkyl/alkoxide exchange requires a fine balance between a Lewis base that is of sufficient strength to cleave the dimeric alkoxide, [R2Al(μ-OR′)]2, while being sufficiently weak to allow dissociation from the monomeric complex, AlR2(OR′)(L).