Reactivity of GaX3 with silylamines and thermal decomposition of the compounds [Cl2Ga{NH(SiMe3)}]2 and [Cl3Ga{NH(SiMe3)2}]

Carmalt, Claire J.; Mileham, John D.; White, Andrew J. P.; Williams, David J.

doi:10.1039/b307763m

Cited by 24 publications

(11 citation statements)

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“…The formation of [MeAlCl 2 {NH(SiMe 2 Ph) 2 }] from [Me 2 AlCl] and NH(SiMe 2 Ph) 2 involved the exchange of one of the methyl groups attached to the aluminum atom with a chlorine atom. These results, along with those obtained by us on some related gallium silylamido complexes, , indicated that the behavior of silylamines with group 13 species is interesting and can lead to unexpected products. We were interested in developing this chemistry further, and in this paper we describe the reactivity of silylamines with a range of organoaluminum complexes.…”

Section: Introductionsupporting

confidence: 73%

Organoaluminum Silylamido Complexes

et al. 2004

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The reaction between [Et2AlCl] and 1 equiv of HN(SiMe3)2 in CH2Cl2 afforded colorless crystals of [Et2AlCl{NH(SiMe3)2}] (1). In contrast, reaction of [Et2AlCl] with 1 equiv of HN(SiMe2H)2 or HN t Bu(SiMe3) resulted in the isolation of dimers, of the type [EtAlCl{NH(R‘)}]2 (2, R‘ = SiMe2H; 3, R‘ = t Bu). Reaction of [Et3Al] with 1 equiv of HN(SiMe2H)2 or HN(SiMe3)2 yielded the expected dimeric complexes, [Et2Al{N(SiMe2H)2}]2 (4) and [Et2Al{N(SiMe3)2}]2 (5), via ethane elimination. The related reaction between [MeAlCl2] and HN t Bu(SiMe3) in CH2Cl2 solution resulted in the formation of the 1:1 adduct [MeAlCl2{NH2( t Bu)}] (6). The structures of compounds 1 and 6 have been determined by X-ray crystallography. In addition, the decomposition of 1 and 6 has been studied by thermal gravimetric analysis.

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Section: Introductionsupporting

confidence: 73%

Organoaluminum Silylamido Complexes

et al. 2004

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“…2.011(4) in NH(SiMe 3 ) 2 ·GaCl 3 , 1.965 (2) in Me 3 Si-N = S = N-SiMe 3 ·GaCl 3 ). [26,27] Finally, it is interesting to note that the previous structure determination of diazene 2 needs to be revised on the basis of our data. [5] Although the cell data are in agreement (space group P2 1 /c, Z = 2), the previously reported structure of 2 was refined without taking into account that the whole molecule is disordered, which results for example in an unrealistically short NÀN bond length of 1.171 (7) and a large N-N-Si angle of 120.0(4)8.…”

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confidence: 92%

Isolation of a Labile Homoleptic Diazenium Cation

Baumann

Michalik

Reiß³

et al. 2014

Angew Chem Int Ed

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Following our interest in nitrogen chemistry, we now describe the synthesis, structure, and bonding of labile disilylated diazene, its GaCl3 adduct, and the intriguing trisilylated diazenium ion [(Me3 Si)2 NN-SiMe3 ](+), a dark blue and highly labile (Tdecomp >-30 °C) homoleptic cation of the type [R3 N2 ](+). Although direct silylation of Me3 Si-N=N-SiMe3 failed, the [(Me3 Si)2 N=N-SiMe3](+) ion was generated in a straightforward two-electron oxidation reaction from mercury(II) dihydrazide and Ag[GaCl4]. Moreover, previous structure data of Me3 Si-NN-SiMe3 were revised on the basis of new data.

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“…Die Ga‐N‐Donor‐Akzeptor‐Bindung in 3 mit 2.036(2) Å25 wird im erwarteten Bereich beobachtet (vgl. 2.011(4) in NH(SiMe 3 ) 2 ⋅GaCl 3 , 1.965(2) Å in Me 3 Si‐NSN‐SiMe 3 ⋅GaCl 3 ) 26. 27…”

Section: Methodsunclassified

Recycling Powered by Release of Carbon Dioxide

2014

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In a cyclic process, fed with external chemical energy generated by the transformation of a compound with high chemical potential to carbon dioxide, the undesired enantiomer from a catalytic asymmetric reaction is continuously recycled to starting reagent. This minor enantiomer recycling is characterized by gradually increasing yields and product enantiomeric ratios. The requirements for maintaining a cyclic procedure are discussed; the necessity of a coupled exergonic process is demonstrated experimentally.Recycling procedures have been invoked in several models for the emergence of homochirality in autocatalytic systems. [1][2][3] Whereas such procedures may be feasible in open systems, incorporation of reverse reactions in models describing closed systems has been subject to intense discussions.[4] As pointed out already by Onsager, in a triangle reaction involving A, B, and C, at equilibrium each transformation is just as likely as its reverse, that is, transformation of A to B takes place as often as transformation of B to A (Scheme 1 a).[5] As each forward and backward reaction must balance, net cycling is not possible; a unidirectional cycle would necessarily involve a thermodynamically uphill process. Continuous addition of a reagent may serve to push the equilibrium for a forward reaction, and consequently for the entire cycle, but this shift does not help the reverse reaction to climb the high energy barrier. However, if a chemical process is performed in a system open to mass flow and coupled to a thermodynamically downhill reaction by transformation of a sacrificial reagent to a by-product with lower chemical potential, a cyclic process operating out of equilibrium may be maintained, [6] in analogy to the way cellular work is powered by adenosine triphosphate through coupling of exergonic to endergonic reactions.Recycling of the undesired enantiomer to achiral starting material may also serve to improve the enantiomeric excess in catalytic reactions. Onsager's example describes an isomerization process, but an analogous situation applies to a reaction network involving an enantioselective reaction with recycling of the minor enantiomer. If the forward, product-forming reaction favors formation of the R enantiomer, the principle of microscopic reversibility states that the reverse reaction cannot favor the reaction of S. However, chemical energy input by influx of a sacrificial reagent (X) with high chemical energy and the removal of compounds (Y and/or Z) with lower energies may serve as the driving force for a cyclic process (Scheme 1 b). [6] For simplicity, it is assumed that the forward reaction of achiral reactant A with reagent X produces a racemic product, that is, k R = k S , in which k R and k S are the rate constants for formation of the R and S enantiomers, respectively, from A, and that the reverse reaction, which restores the starting reagent and produces by-products Y and Z, proceeds with high selectivity, such that k' R % 0, for which k' R is the rate constant for decomposition of the R ...

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Reactivity of GaX3 with silylamines and thermal decomposition of the compounds [Cl2Ga{NH(SiMe3)}]2 and [Cl3Ga{NH(SiMe3)2}]

Cited by 24 publications

References 28 publications

Organoaluminum Silylamido Complexes

Organoaluminum Silylamido Complexes

Isolation of a Labile Homoleptic Diazenium Cation

Recycling Powered by Release of Carbon Dioxide

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