X-ray crystal structure of trimethylsilylmethyllithium

Tecle, Berhan.; Rahman, Abdur; Oliver, John P.

doi:10.1016/0022-328x(86)80537-x

Cited by 75 publications

(38 citation statements)

References 24 publications

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“…[9] Of course it is not prudent to surmise that larger anions or larger polydentate donors will automatically result in smaller aggregates since electronic factors will also play an important role. While lithium complexes are often smaller (and consequently more soluble) oligomers, heavier sodium and potassium derivatives have a tendency to give larger insoluble polymers; for example, hexameric LiCH 2 SiMe 3 [10] is commercially available as a hexane solution yet its K congener is insoluble in the same medium. [11] Whereas judicious choice of anion and Lewis donor can disrupt the polymerization of lithium species, it is much more arduous to do so with Na or K complexes of simple organic anions.…”

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confidence: 99%

Exploiting σ/π Coordination Isomerism to Prepare Homologous Organoalkali Metal (Li, Na, K) Monomers with Identical Ligand Sets

Davidson

García‐Vivó

Kennedy

et al. 2011

Chemistry A European J

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Tetraamine Me(6)TREN has been used as a scaffold support to provide coordinative saturation in the complexes PhCH(2)M⋅Me(6)TREN (M=Li, Na, K). The Li derivative displays a Li−−C σ interaction with a pyramidalized CH(2) both in the solid state and in solution, and represents the first example of η(4) coordination of Me(6)TREN to lithium. In the sodium derivative, the metal cation slips slightly towards the delocalized π electrons whilst maintaining a partial σ interaction with the CH(2) group. For the potassium case, coordinative saturation successfully yields the first monomeric benzylpotassium complex, in which the anion binds to the metal cation exclusively through its delocalized π system resulting in a planar CH(2) group.

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confidence: 99%

Exploiting σ/π Coordination Isomerism to Prepare Homologous Organoalkali Metal (Li, Na, K) Monomers with Identical Ligand Sets

Davidson

García‐Vivó

Kennedy

et al. 2011

Chemistry A European J

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“…Surprisingly, considerably less is known about the alkali metal compounds of the smallest and simplest member of this family of silyl-substituted methyl groups, namely the (trimethylsilyl)methyl (CH 2 SiMe 3 ) or monosyl group. [20] Again, the most examined (trimethylsilyl)methyl compound to date is the lithium congener, [(trimethylsilyl)methyl]lithium [Me 3 SiCH 2 Li] n , which is known to form a hexamer (n = 6) in the solid state, [21] whereas both N,N,NЈ,NЈ-tetramethylethylenediamine (TMEDA) and the (-)-sparteine adducts form dimers (n = 2), and the higher-denticity ligand N,N,NЈ,NЈЈ,NЈЈ-pentamethyldiethylenetriamine (PMDETA) forms a monomer (n = 1). [22] [(Trimethylsilyl)methyl]potassium has been used in C-metallation reactions of cyclohexene, [23] toluene, [24] and tetrahydrofuran, [25] and in an N-metallation reaction of a secondary amine to form potassium 2,2,6,6-tetramethylpiperidide [26] in situ, [27] which has recently been employed as a convenient precursor in synergic mixed-metal chemistry.…”

Section: Alkylmetal Compoundmentioning

confidence: 99%

Synthesis and Structures of [(Trimethylsilyl)methyl]sodium and ‐potassium with Bi‐ and Tridentate N‐Donor Ligands

et al. 2011

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[(Trimethylsilyl)methyl]sodium [NaCH2SiMe3] (1) was prepared by a metathesis reaction of [(trimethylsilyl)methyl]lithium [LiCH2SiMe3] with sodium tert‐butoxide in n‐hexane. Polydentate donors such as N,N,N′,N′‐tetramethylethylenediamine (TMEDA) and N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) form n‐hexane‐soluble complexes of 1 and the potassium congener [KCH2SiMe3] (2). The crystal structures of the polymers [(TMEDA)NaCH2SiMe3] (1a) and [(PMDETA)KCH2SiMe3] (2a) were determined as infinite helical chains exhibiting 31 or 32 screw‐axis symmetry. Compound 2b was obtained as the donor‐deficient heterocubane pseudotetramer [(TMEDA)3(KCH2SiMe3)4], with intermolecular interactions of the TMEDA‐uncoordinated potassium atom with a peripheral methyl group of a neighbouring tetramer to form infinite chains. The relatively easy accessibility and stability should make these (trimethylsilyl)methyl compounds of sodium and potassium valuable starting points for further exploration of the chemistry of these common‐utility heavier alkali metals.

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“…[9] To date only the donor free molecular structure of trimethylsilylmethyllithium [LiCH 2 SiMe 3 ] 6 (1) has been reported. [10] Because of the excellent storage features of crystalline trimethylsilylmethyllithium, it is perfectly applicable in silyl transfer reactions. [11] Herein, we report on the deaggregation of the hexameric trimethylsilylmethyllithium (1) with the nitrogen donor cbases TMEDA, (-)-sparteine and N,N,NЈ,NЈЈ,NЈЈ-pentamethyldiethylenetriamine (PMDETA) (Figure 1) [(TMEDA)·LiCH 2 SiMe 3 ] 2 (2) crystallises in the monoclinic space group P2 1 /n ( Figure 2).…”

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Deaggregation of Trimethylsilylmethyllithium

Tatić

Ott

2008

Eur J Inorg Chem

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Polyamine donor bases such as N,N,N′,N′‐tetramethylethylenediamine (TMEDA), (–)‐sparteine and N,N,N′,N″,N″‐pentamethyldiethylentriamine (PMDETA) have been employed to deaggregate parent trimethylsilylmethyllithium (1). The crystal structures of the dimers [(TMEDA)·LiCH2SiMe3]2 (2) and [{(–)‐sparteine}·LiCH2SiMe3]2 (3) were determined and reveal a four‐membered ring as the central structural motif. The two lithium atoms are each coordinated by the chelating ligands and the carbanions. The Li–C contacts show alternating bond lengths. The monomer [(PMDETA)·LiCH2SiMe3] (4) has the shortest Li–C contact of the aggregates discussed, and the Me3Si group points toward the central nitrogen atom of the PMDETA ligand, even if this alignment seems unfavourable for steric reasons. The bond lengths and angles of compounds 2–4 are discussed in relation to the orientation of the lone pair at the carbanion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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X-ray crystal structure of trimethylsilylmethyllithium

Cited by 75 publications

References 24 publications

Exploiting σ/π Coordination Isomerism to Prepare Homologous Organoalkali Metal (Li, Na, K) Monomers with Identical Ligand Sets

Exploiting σ/π Coordination Isomerism to Prepare Homologous Organoalkali Metal (Li, Na, K) Monomers with Identical Ligand Sets

Synthesis and Structures of [(Trimethylsilyl)methyl]sodium and ‐potassium with Bi‐ and Tridentate N‐Donor Ligands

Deaggregation of Trimethylsilylmethyllithium

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