Silicon halides formation

An interesting variant of metal-silicon bond formation is the combination of metal halides with silyl anions. Since silyl dianions are not available, only one metal-silicon bond can be formed directly. The silylene complexes are then accessible by subsequent reaction steps [113], An example of this approach is given by the reaction of cis-bistriethylphosphaneplatinumdichloride 25 with diphenylsilylli-thium, which yields, however, only dimeric platinadisilacyclosilanes 26a-c [114]. 

A reaction of special interest occurs with triethylamine and has been described by Urry et al. J24 327, 436, 646, 647. Triethylamine catalyses conversion of Si2Cl6 to higher silicon halides such as SisCl12 and Si6Cli4, besides SiCl4672). Urry believes that adduct formation with me3N initiates the reaction ... 

Formation of inorganic silicohalides via silicohalide-mercury compounds is also possible (see Chapter 3 Silicon Halides with Si-Si Bonds) ... 

This reaction made numerous silicon compounds available and even today is still of great importance. Kipping expected to find an analogy between silicon and carbon compounds, but his later papers reveal his disappointment in the lack of versatility and limited reactivity of silicon compounds. Kipping was rather pessimistic about the further development of organosilicon chemistry, being so much influenced by ideas of carbon chemistry that he underestimated the importance of the formation of the siloxanes from the silicon halides, as now evidenced in the industrial applications of organosilicon compounds. 

The reaction may involve the intermediate formation of a metal hydride which undergoes metathesis with the silicon halide, but no evidence for such a mechanism has been accumulated. 

The fluorovinyllithium reagents are thermally unstable (vu/e supra) and are reacted with electro-philes at low temperatures. These reagents undergo usual reactions with a variety of electrophiles including ketones, esters, alkanoyl chlorides, epoxides (e.g.. formation of 6 ), oxetanes, carbon dioxide, sulfur dioxide, tin and silicon halides, and trifluoromethancsulfonates. The reaction of 2,2-difluoro-1 -(tosyloxy)vinyllithium (5) with trialkylboranes followed by a second electrophile is an attractive route to functionalized 1.1-difluoroalkenes. e.g. 7. ... 

Formation of Silicon-Transition and Inner Transition-Metal Bond 239 5 8.3.3. from Silicon Halides... 

Reaction with HC02CoMe S.8.2.9.2 Reaction with Me3SiI S.8.3.S.2 Reaction with silicon halides S.8.3.3.1 C4HCl3Fe04Si Fe(SiCl3XHXCO)4 Formation S.8.3.2.3... 

The formation of silicon nitride whiskers was observed in several different reactions, including vapor deposition, CVD, and growth from a melt. However, only the following techniques are considered to have commercial significance nitriding of metallic silicon or silicon-silica mixture, carbothermal reduction of silica with simultaneous nitridation, and thermal decomposition of silicon halides. 

The synthesis of organosilicon compounds (i.e., formation of the Si—C bond) starting from a silicon halide and an organometallic compound (RMgX, LiR) (9, H, 60) is well known ... 

B. CARBON-SILICON BOND FORMATION B.i. Reactions of Aryl, Alkyl, and Benzyl Halides... 

The use of silicon halides for purification of melts used to grow single ciystals does not lead to formation of additional impurities, because the processes are carried out in quartz (i.e., Si02) containers. 

Isomerically pure 1 is obtained when HMes2SiSiPh2SiPh2SiMes2H (Mes = mesityl) 5 is used as a starting material, because bonds between silicon and methyl substituted aryl groups like p-tolyl or mesityl are cleaved much faster by hydrogen halides than Si-Ph bonds [3], Further reaction of I with HCl or HBr leads to the formation of the corresponding halo-derivatives 2 and 3 ... 

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