- A simple synthesis of tetrabromosilane
-
We report on a synthesis of SiBr4 by reacting C6H5SiBr3 with HBr/AlBr3 to give a nearly quantitative yield. We start from C6H5SiCl3 which gives C6H5SiH3 with LiAlH4 and further on C6H5SiBr3 with Br2. Johann Ambrosius Barth 1996.
- Horn, Hans-Georg,Kuczkowiak, Dirk
-
-
Read Online
- Halide-Ion Diadducts of Perhalogenated Cyclopenta- and Cyclohexasilanes
-
The halosilicates(II) [nBu4N]2[Si6Br12·2Br] and [nBu4P]2[Si6I12·2I] were prepared by mere addition of the appropriate halide salt to the corresponding disilane Si2X6 (X = Br, I). In the first case, the Br3Si-substituted derivative [nBu4N]2[Si7Br14·2Br] formed as a second product. We have been able to obtain single crystals of [Ph4P]2[Si7Br14·2Br] by switching the Br– salt from [nBu4N]Br to [Ph4P]Br. All three compounds, [nBu4N]2[Si6Br12·2Br] (monoclinic, P21/c), [nBu4P]2[Si6I12·2I] (triclinic, P1), and [Ph4P]2[Si7Br14·2Br] (triclinic, P1) were structurally characterized by X-ray crystallography and found to form “inverse sandwich complexes”, in which two X– ions are located above and below a planarized Si6 ring. The free periodated cyclohexasilane Si6I12 is accessible from [nBu4N]2[Si6Cl12·2Cl] and BI3 (1:5 molar ratio; CH2Cl2) via a decomplexation/halide-exchange cascade. Si6I12 (monoclinic, C2/c) adopts a puckered chair conformation in the solid state. The cyclopentasilane diadduct [nBu4P]2[Si5Cl10·2Cl] forms at –78 °C from Si5Cl10 and 2 equiv. of [nBu4P]Cl in CH2Cl2. An X-ray analysis of [nBu4P]2[Si5Cl10·2Cl]·2CH2Cl2 (monoclinic, C2/c) again revealed the structure of an “inverse sandwich complex”. Crystalline [nBu4P]2[Si5Cl10·2Cl]·2CH2Cl2 is stable at room temperature. However, in CH2Cl2 solution the compound quantitatively undergoes ring-expansion reactions to furnish cyclohexasilane derivatives. This behavior is in striking contrast to that of [nBu4N]2[Si6Cl12·2Cl], which persists at room temperature both in solution and the solid state. Competition experiments revealed free Si5Cl10 and Si6Cl12 to have comparable Cl– affinities, even though the distance between the two apical Cl– ions in [Si5Cl10·2Cl]2– (4.292 ?) is larger by 0.456 ? than that in [Si6Cl12·2Cl]2– (3.836 ?).
- Teichmann, Julian,K?stler, Benedikt,Tillmann, Jan,Moxter, Maximilian,Kupec, Robin,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
-
-
Read Online
- Silicon Tetrakis(trifluoromethanesulfonate): A Simple Neutral Silane Acting as a Soft and Hard Lewis Superacid
-
A facile synthesis and isolation of pristine silicon tetrakis(trifluoromethanesulfonate), Si(OTf)4, is reported, acting as the first neutral silicon-based Lewis superacid suitable towards soft and hard Lewis bases. Its OTf groups have a dual function: they are excellent leaving groups and modulate the degree of reactivity towards soft and hard Lewis bases. Exposed to soft Lewis donors, Si(OTf)4 leads to [L2Si(OTf)4] complexes (L=isocyanide, thioether and carbonyl compounds) with retention of all Si?OTf bonds. In contrast, it can cleave C?X bonds (X=F, Cl) of hard organic Lewis bases with a high tendency to form SiX4 (X=F, Cl) after halide/triflate exchange. Most notable, Si(OTf)4 allows a gentle oxydefluorination of mono- and bis(trifluoromethyl)benzenes, resulting in the formation of the corresponding benzoylium species, which are stabilized by the weakly coordinating [Si(OTf)6] dianion.
- Driess, Matthias,Hermannsdorfer, André
-
supporting information
p. 13656 - 13660
(2021/05/03)
-
- [2+2+1]cycloadditions of bis(dialkylamino)acetylenes with SiI 2(Idip): Syntheses and reactivity studies of unprecedented 2,3,4,5-tetraamino-1 H-siloles
-
A novel method for the synthesis of 1H-siloles is presented. It involves a [2+2+1] cycloaddition of the ynediamines R2N-C≡C-NR2 (R=Me, Et) with SiI2(Idip) (Idip=1,3-bis(2,6-diisopropylphenyl) imidazolin-2-ylidene) to affor
- Lebedev, Yury N.,Das, Ujjal,Chernov, Oleg,Schnakenburg, Gregor,Filippou, Alexander C.
-
p. 9280 - 9289
(2014/08/05)
-
- Reaction of Silicon Difluoride with Halogens: a Reinvestigation
-
Reactions of SiF2 with halogens have been reinvestigated by both co-condensation and gas-phase methods.The co-condensation method yields a number of fluorohalogenosilanes including mono-, di-, and higher silane derivatives.These compounds contain SiF, SiF2, and SiF3 units.The reactivity towards SiF2 decreases from chlorine through bromine to iodine.While chlorine and bromine give rise to a number of fluorohalogenosilanes, iodine yields only the monosilane derivatives.In contrast, the gas-phase reaction do not progress to any appreciable extent.The products have been characterized by mass spectrometry and 19F and 29Si n.m.r. spectroscopy.Many have been identified for the first time.
- Suresh, Bettadapura S.,Thompson, James Charlton
-
p. 1123 - 1126
(2007/10/02)
-