Synthese und Struktur von Lithium‐tris(trimethylsilyl)silanid · 1,5 DME

Becker, Gerd; Hartmann, Hans-Martin; Münch, Angelika; Riffel, H.

doi:10.1002/zaac.19855301104

Cited by 80 publications

(50 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Bond lengths and bond angles are nearly identical in the two structures indicating similar pn-dn bonding between Si and N atoms. A number of Li-and Na-containing bis(trimethylsilyl)amide crystal structures are also known and can be compared with the potassium bis ( Murray & Power (1984a,b); Becker, Hartmann, Munch & Riffel (1985).…”

Section: Lengths (A) and Bond Angles (O)mentioning

confidence: 99%

Structure of potassium hexamethyldisilazide toluene solvate

Williard¹

1988

Acta Crystallogr C Cryst Struct Commun

View full text Add to dashboard Cite

Abstract. K[C6HIsNSi2].CvHs, Mr=291.62, monoclinic, C2/c, a= 13.213 (5), b= 17.077 (4), c= 15.796 (4) A, fl= 95.66 (2) °, V= 3546.8 (1.2) A 3, Z =8, D x= l.09gcm -3, 2(MoKa)=0.71069A, /t= 4.08 cm -1, F(000) = 1264, T,,,173 K. Final R = 0.045 for 2062 unique observed reflections. The compound was found to be a dimeric aggregate, the core of which consists of a nearly planar K--N-K--N four-membered ring. The crystallization solvent, toluene, co-crystallizes with the dimer but is not coordinated. Bond lengths and angles are in agreement with those of the monomeric dioxane-solvated compound.

show abstract

Section: Lengths (A) and Bond Angles (O)mentioning

confidence: 99%

Structure of potassium hexamethyldisilazide toluene solvate

Williard¹

1988

Acta Crystallogr C Cryst Struct Commun

View full text Add to dashboard Cite

show abstract

“…The four-coordinate lithium ion binds tripodally to the three methoxy groups, and bridges each of the {Si(SiO) 3 Li} units with the negatively charged central silicon. The Si4-Li distance (276.3 pm) in 4 is significantly longer than in the closely related hypersilanides [(Me 3 Si) 3 SiLi(dme) 1.5 ] (263 pm), [10] [(Me 3 Si) 3 SiLi(thf) 3 ] (264 pm), [11] [(Me 3 Si) 3 Si(mLi)] 2 (267 pm), [12] and [(Me 3 Si)Si(m-Li(thf))] 2 (271 pm).[13] The Si-Si-Si angles are reduced from an ideal tetrahedral value of 109.58 as in Si(SiMe 3 ) 4 to an average value of 988 in 4. These findings show that ionic interactions are predominant Scheme 1.…”

mentioning

confidence: 98%

The Multidentate Ligand (MeOMe₂Si)₃Si⁻: Unusual Coordination Modes in Alkali Metal Silanides

2007

View full text Add to dashboard Cite

Alkali metal silanides, R 3 SiM (R = alkyl, aryl, silyl) [1] are important reagents in the synthesis of compounds with silicon-silicon bonds, such as disilenes, [2] disilynes, [3] silicon clusters, [4] and oligosilane dendrimers. [5] In the solid state, the majority of these silanides form either solvated monomers, such as [R 3 SiM(donor) n ] (M = Li, Na, K, Rb, Cs; donor = THF, TMEDA (N,N,N',N'-tetramethylethylenediamine), DME (1,2-dimethoxyethane), C 6 H 6 , [18] [1f] Herein we report that lithium, sodium, and potassium derivatives of the new ligand Si(SiMe 2 OMe) 3 (trimethoxyhypersilanide) have very different structures, crystallizing as a result of strong coordinative interactions of the methoxy groups to the metal centers as clusters (K) or polymeric chains (Li, Na).[6] NMR spectroscopic investigations show that even in THF solutions, in which these aggregates dissociate into monomers, intramolecular oxygen-to-metal coordination is maintained.The synthetic route to the metal trimethoxyhypersilanides 4-6 is given in Scheme 2. Reaction of (Me 3 Si) 4 Si (1) with AlCl 3 and acetyl chloride furnishes (ClMe 2 Si) 4 Si (2) in 90-95 % yield. [7] Compound 2 was converted into tetrakis(methoxydimethylsilyl)silane, (MeOMe 2 Si) 4 Si, (3) in about 90 % yield by reaction with HC(OMe) 3 in the presence of catalytic amounts of AlCl 3 . Finally, the lithium, sodium, and potassium trimethoxyhypersilanides 4-6 were obtained upon treatment of MOtBu (M = Li, Na, K, respectively) with 3 in THF at room temperature. These reactions proceed smoothly to give 6 within about two hours, and 4 and 5 in about 10-12 hours, and were essentially quantitative according to NMR spectroscopic measurements. In contrast, the reaction of (Me 3 Si) 4 Si with NaOtBu or LiOtBu does not give the related hypersilanides (Me 3 Si) 3 SiLi and (Me 3 Si) 3 SiNa under similar conditions; no reaction occurred even after three days at room temperature.[8] Evidently, the methoxy groups of 3 significantly increase the electrophilicity of the silicon atoms of the SiMe 2 OMe groups and consequently facilitate selective Si À Si bond cleavage by nucleophilic attack of the tert-butoxide anion.The colorless trimethoxyhypersilanides 4-6 are surprisingly thermally stable. Upon increasing the temperature to 55 8C in [D 8 ]THF, no structurally irreversible changes, such as protonation, elimination of methoxide, skeletal rearrangements to metal siloxides, or condensation reactions to polysilanes, occurred. In the solid state, 4-6 began to decompose only above 200 8C, with formation of reddishbrown liquids. The solubility of 4 and 5 in organic solvents differs significantly from that of 6. The latter readily dissolves in THF and hydrocarbons such as benzene, toluene, and nhexane, whereas the lithium and sodium derivatives are almost insoluble in benzene and n-hexane.The solid-state structures of 4-6 were determined by Xray crystallography, [9] and the results are shown in Figure 1-3 along with selected average bond lengths and angles in Table 1. Lithium silanide 4 (F...

show abstract

“…( M= K, donor = [18]crown-6, n = 1, 1; Rb, donor = [18]crown-6, n = 1, 4; and M = K, donor = TMEDA, n = 2, 6). The silicon analogue of 6, [K(tmeda) 2 8).…”

Section: Introductionmentioning

confidence: 99%

“…Examples include the lithium silanides [LiSi(SiMe 3 ) 3 ], [15] [Li(thf) 3 Si-(SiMe 3 ) 3 ], [16,17] [Li(thf) 3 Si(SiMe 3 ) 3 ][Si(SiMe 3 ) 4 ], [16] and [Li-(dme) 1.5 Si(SiMe 3 ) 3 ] (DME= 1,2-dimethyloxyethane). [18] Other silanides include an etherate of KSiPh 3 , initially prepared by Gilman and Wu in 1951 by cleaving the silicon-silicon bond in hexaphenyldisilane with an Na-K alloy, followed by analogous chemistry for rubidium and cesium. [19] Later work by Wiberg et al focused on the treatment of alkali-metal halides dissolved in ammonia with hexaphenyldisilanes.…”

Section: Introductionmentioning

confidence: 99%

Syntheses and Structures of the First Heavy‐Alkali‐Metal Tris(trimethylsilyl)germanides

Teng

Ruhlandt‐Senge

2005

Chemistry A European J

View full text Add to dashboard Cite

The first heavy-alkali-metal tris(trimethylsilyl)germanides were obtained in high yield and purity by a simple one-pot reaction involving the treatment of tetrakis(trimethylsilyl)germane, Ge(SiMe3)4, with various alkali metal tert-butoxides. The addition of different sizes of crown ethers or the bidentate TMEDA (TMEDA=N,N,N',N'-tetramethylethylenediamine) provided either contact or separated species in the solid state, whereas in aromatic solvents the germanides dissociate into separated ions, as shown by 29Si NMR spectroscopic studies. Here we report on two series of germanides, one displaying M-Ge bonds in the solid state with the general formula [M(donor)n Ge(SiMe3)3] (M=K, donor=[18]crown-6, n=1, 1; Rb, donor=[18]crown-6, n=1, 4; and M=K, donor=TMEDA, n=2, 6). The silicon analogue of 6, [K(tmeda)2Si(SiMe3)3] (7) is also included to provide a point of reference. The second group of compounds consists of separated ions with the general formula [M(donor)2][Ge(SiMe3)3] (M=K, donor=[15]crown-5, 2; M=K, donor=[12]crown-4, 3; and M=Cs, donor=[18]crown-6, 5). While all target compounds are highly sensitive towards hydrolysis, use of the tridentate nitrogen donor PMDTA (PMDTA=N,N,N',N'',N''-pentamethyldiethylenetriamine) afforded even more reactive species of the composition [K(pmdta)2Ge(SiMe3)3] (8). We also include the silanide analogue [K(pmdta)2Si(SiMe3)3] (9) for sake of comparison. The compounds were typically characterized by X-ray crystallography, and 1H, 13C, and 29Si NMR and IR spectroscopy, unless extremely high reactivity, as observed for the PMDTA adducts 8 and 9, prevented a more detailed characterization.

show abstract

Synthese und Struktur von Lithium‐tris(trimethylsilyl)silanid · 1,5 DME

Cited by 80 publications

References 42 publications

Structure of potassium hexamethyldisilazide toluene solvate

Structure of potassium hexamethyldisilazide toluene solvate

The Multidentate Ligand (MeOMe₂Si)₃Si⁻: Unusual Coordination Modes in Alkali Metal Silanides

Syntheses and Structures of the First Heavy‐Alkali‐Metal Tris(trimethylsilyl)germanides

Contact Info

Product

Resources

About

Synthese und Struktur von Lithium‐tris(trimethylsilyl)silanid · 1,5 DME

Cited by 80 publications

References 42 publications

Structure of potassium hexamethyldisilazide toluene solvate

Structure of potassium hexamethyldisilazide toluene solvate

The Multidentate Ligand (MeOMe2Si)3Si−: Unusual Coordination Modes in Alkali Metal Silanides

Syntheses and Structures of the First Heavy‐Alkali‐Metal Tris(trimethylsilyl)germanides

Contact Info

Product

Resources

About

The Multidentate Ligand (MeOMe₂Si)₃Si⁻: Unusual Coordination Modes in Alkali Metal Silanides