Crystal and molecular structure of tribenzylaluminum, a novel .eta.1-arene coordinated structure

Rahman, Abdur; Siddiqui, Kaniz F.; Oliver, John P.

doi:10.1021/om00066a026

Cited by 31 publications

(10 citation statements)

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“…The aluminum−nitrogen bond is also similar to that ascertained for 1 , although the slightly longer silicon−amide bond (1.745(5) vs 1.72(1) Å) coupled with the marginally shorter Al−N bond (1.853(5) vs 1.89(1) Å) may point to a slightly higher degree of π-donation from the amide lone pair to the metal. Compound 4 also possesses unremarkable aluminum−carbon bond lengths of 1.991(7) and 1.987(6) Å, which are akin to those previously reported for terminal Al−C bonds. ,,,− The strongest similarity is with the Al−C distances found in Al(CH 2 C 6 H 5 ) 3 , for which average values of 1.989(6) Å were found …”

Section: Resultssupporting

confidence: 69%

Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe₂CH₂PPrⁱ₂)₂

et al. 1996

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The preparation of new four-and five-coordinate aluminum amido diphosphine complexes is reported. The reaction of the potentially tridentate ligand precursor LiN(SiMe 2 CH 2 PPr i 2 ) 2 with AlCl 3 in toluene at 25°C leads to the formation of AlCl 2 [N(SiMe 2 CH 2 PPr i 2 ) 2 ]. The X-ray crystal structure shows it to be monomeric with a distorted-trigonal-bipyramidal geometry having the tridentate ligand meridionally bound. The solution NMR spectra are also consistent with this geometry. Addition of the alkyllithium reagents RLi (where R ) Me, Et) or dialkyl magnesium reagents R 2 Mg (R ) Me, CH 2 Ph) leads to the formation of bis-(hydrocarbyl) derivatives of the formula AlR 2 [N(SiMe 2 CH 2 PPr i 2 ) 2 ]. The X-ray structure of Al(CH 2 Ph) 2 [N(SiMe 2 CH 2 PPr i 2 ) 2 ] shows that it is mononuclear in the solid state with a distorted-tetrahedral geometry in which coordination to only one phosphine is observed. Variable-temperature NMR studies are consistent with a rapidly fluxional molecule at ambient temperature. In solution, the NMR spectroscopic parameters of AlMe 2 [N(SiMe 2 -CH 2 PPr i 2 ) 2 ] and AlEt 2 [N(SiMe 2 CH 2 PPr i 2 ) 2 ] are consistent with overall C 2v symmetry. These observations are supported by 27 Al NMR studies. Attempts to generate the monoalkyls Al(R)X[N(SiMe 2 CH 2 PPr i 2 ) 2 ] (R ) Me, Et; X ) Cl) by the addition of 1 equiv of the appropriate alkylating reagent results in equimolar mixtures of the corresponding dialkyl and dichloride; however, the reaction of the lithium salt LiN(SiMe 2 CH 2 PPr i 2 ) 2 with RAlCl 2 (R ) Me, Et) produces mixtures containing predominantly Al(R)X[N(SiMe 2 CH 2 PPr i 2 ) 2 ] (R ) Me, Et). Treatment of the monoethyl derivative with excess AlCl 3 affords AlCl 2 [N(SiMe 2 CH 2 PPr i 2 ) 2 ]‚ AlCl 3 . The X-ray crystal structure of this compound shows it to be monomeric, with each phosphine bound to a tetrahedral Al center. Solution NMR studies are consistent with this geometry. This species is likely formed as the result of the coordination of an AlCl 3 molecule to the aluminum center, followed by coordination of a second molecule to a free phosphine and subsequent elimination of EtAlCl 2 . This species is also generated by the addition of 3 equiv AlCl 3 to the starting lithium salt LiN(SiMe 2 CH 2 PPr i 2 ) 2.

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Section: Resultssupporting

confidence: 69%

Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe₂CH₂PPrⁱ₂)₂

et al. 1996

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“…One such interaction was found in the crystal structure of 8 (AlMe 2 ) 6 , where one [AlMe 2 ] + group connects to one N(exo) site and, in addition, makes a loose contact with a phenyl ring. A similar interaction, albeit shorter and intermolecular in nature, was observed in crystals of tribenzylaluminum …”

Section: Discussionsupporting

confidence: 64%

“…A similar interaction, albeit shorter and intermolecular in nature, was observed in crystals of tribenzylaluminum. 54 In this series, [AlMe 2 ] + is the primary product of metalation while [AlMe] 2+ is produced only at the later stages either to mitigate overcrowding or to facilitate aggregation. Integration of the small and formally dicationic [AlMe] 2+ unit offsets two deprotonation steps but takes considerably less space than two [AlMe 2 ] + groups.…”

Section: Inorganic Chemistrymentioning

confidence: 99%

Polyanionic Ligand Platforms for Methyl- and Dimethylaluminum Arrays

et al. 2019

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Trimethylaluminum finds widespread applications in chemical and materials synthesis, most prominently in its partially hydrolyzed form of methylalumoxane (MAO), which is used as a cocatalyst in the polymerization of olefins. This work investigates the sequential reactions of trimethylaluminum with hexaprotic phosphazenes (RNH)6P3N3 (=XH6) equipped with substituents R of varied steric bulk including tert-butyl (1H6), cyclohexyl (2H6), isopropyl (3H6), isobutyl (4H6), ethyl (5H6), propyl (6H6), methyl (7H6), and benzyl (8H6). Similar to MAO, the resulting complexes of polyanionic phosphazenates [XH n ] n−6 accommodate multinuclear arrays of [AlMe2]+ and [AlMe]2+. Reactions were monitored by 31P NMR spectroscopy, and structures were determined by single-crystal X-ray diffraction. They included 1H4(AlMe2)2, 1H3(AlMe2)3, 2H3(AlMe2)3, 3(AlMe2)4AlMe, 4H(AlMe2)5, 4(AlMe2)6, {5H(AlMe2)4}2AlMe, 5(AlMe2)6, 6(AlMe2)6, {7(AlMe2)4AlMe}2, and 8(AlMe2)6. The study shows that subtle variations of the steric properties of the R groups influence the reaction pathways, levels of aggregation, and fluxional behavior. While [AlMe2]+ is the primary product of the metalation, [AlMe]2+ is utilized to alleviate overcrowding or to aid aggregation. At the later stages of metalation, [AlMe2]+ groups start to scramble around congested sites. The ligands proved to be very robust and extremely flexible, offering a unique platform to study complex multinuclear metal arrangements.

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“…234 "C, in 17% yield, and photolysis in solution gave the digermene. This species is apparently stable, but Ar (10) ArMC,, L ~+ N ~~' , D M E 1 ' ; hw,C,D,,, \ /Ar…”

Section: Groupivmentioning

confidence: 99%

“…Certainly the small size of the lithium attracts quantum mechanical calculations which may well have useful predictive and interpretive value in this area. A recent example is the structure of dilithiated propene, (Li2C3H4), for which an initio 3-21G//3-2 1G calculations indicate that symmetrical double-bridging structures such as (10) are energetically most f a v 0 ~r e d . l ~…”

Section: Phzpmentioning

confidence: 99%

Chapter 12. Organometallic chemistry. Part (ii) Main-group elements

Kennedy¹

1982

Annu. Rep. Prog. Chem., Sect. B

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It is of interest to note here, incidently, that the unsubstituted silabarellene (25), like barellene itself, undergoes photochemical rearrangement to the 1 -silasemibullvalene (26). In contrast to semibullvalene itself, however, which undergoes a degenerate 3,3-shift at -150 "C with an activation energy of only 20 kJ mol-', the 1 -sila-species appears to be static, even at + 150 0C.40Returning to the sila-alkenes, however, it is obviously much more satisfactory to have stable species to examine, and in this regard 1982 has been an exciting year. The stable silaethylene [(Me3Si),Si=C(OSiMe3)(Cl0H15)3 (where CloH15 =

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Crystal and molecular structure of tribenzylaluminum, a novel .eta.1-arene coordinated structure

Cited by 31 publications

References 0 publications

Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe₂CH₂PPrⁱ₂)₂

Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe₂CH₂PPrⁱ₂)₂

Polyanionic Ligand Platforms for Methyl- and Dimethylaluminum Arrays

Chapter 12. Organometallic chemistry. Part (ii) Main-group elements

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Crystal and molecular structure of tribenzylaluminum, a novel .eta.1-arene coordinated structure

Cited by 31 publications

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Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe2CH2PPri2)2

Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe2CH2PPri2)2

Polyanionic Ligand Platforms for Methyl- and Dimethylaluminum Arrays

Chapter 12. Organometallic chemistry. Part (ii) Main-group elements

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Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe₂CH₂PPrⁱ₂)₂

Synthesis and Characterization of Four- and Five-Coordinate Organoaluminum Complexes Incorporating the Amido Diphosphine Ligand System N(SiMe₂CH₂PPrⁱ₂)₂