Silicon-chlorine bonds

It was found that silicon-bromine and silicon-chlorine bonds were thermodynamically activated towards substitution by coordination of an oxygen nucleophile, whereas coordination was found to deactivate the silicon-fluorine bond. 

Chlorosilane. A chlorine derivative of a silane a compound containing at least one silicon-chlorine bond. 

Monochlorosilane. The compound HsSiCl in general, a compound of silicon containing only one silicon-chlorine bond. 

Moreover, the kinetic curves (obtained from GC analysis) of the electrochemical reduction of PhMeSiCl2 with an A1 anode, as an example, show that the two silicon-chlorine bonds are reduced in two well-separated steps (Fig. 2) ... 

The arsenic acids have no structural parallel in the heavier elements of Group IV (Si, Ge, Sn, Pb) but appear to function as a carboxylic acid would in ring-closure reactions. The contrast in behavior of an As—Cl bond toward electrophilic attack on a benzene ring versus Si—Cl reactivity should be noted. No clear-cut examples of a Friedel-Crafts reaction involving a silicon-chlorine bond have been reported 107). 

We would like to suggest, that an attack of a chlorine takes place first at one of the silicon atoms of the tri- or tetrasilane under discussion to form a pentacoordinated silicon. In a second step, a silylene is generated which inserts into a silicon-chlorine bond of the disilane while the silicon skeleton of the oligosilane is shortened by one silicon atom. The source of the attacking chlorine is not yet known An intramolecular reaction with a chlorine of a chloromethylsilyl-sidechain and the central silicon might occur, or remaining traces of the aluminium trichloride, used for the chlorination, might induce the reaction. This is possible since only catalytic amounts would be necessary to cause the decomposition. 

Hexachlorodisiloxane is a colorless liquid boiling at 137°. It is the first member of the open-chain series of oxy-halides of general composition Si 0 -iCl2n+2. The reactivity of the silicon-chlorine bond in the molecule is... 

Baney and Gaul synthesized methylchloropolysilane from disilanes ( i-Si=) by redistribution reactions of silicon-chlorine/silicon-silicon bonds [9,10]. Distilled mixed disilanes were catalytically rearranged with tetrabutylphosphonium chloride (1%) to produce preceramic polymer. The polymer obtained is considered to have a polycyclic -Si-Si- chain. The structural units are sSi (CH3), =Si(CH3)2, and =Si(CH3)Cl. Several new polymers were derived from methylchloropolysilane by substituting the remaining silicon-chlorine bonds by other chemical groups [11]. 

Binding to the phosphoramide polarizes the silicon-chlorine bonds, leading to ionization of a chloride and formation of a catalytically active, pentacoordinated trichloro-silyl cation 110. From this point of view, this example will be discussed also in the section on Lewis-acid-catalyzed aldol reactions. 

Knowing that the reduction potentials of dichlorosilanes are much less cathodic than that of Me3SiCl, we can assume that the dichlorosilanes are first reduced to monochlorosilyl anions which are then trapped by the Me3SiQ present in large excess rather than by the dichlorosilane. Moreover, the kinetic curves (obtained from GC analysis) of the electrochemical reduction of PhMeSiCl2 with an A1 anode, as an example, show that the two silicon-chlorine bonds are reduced in two well-separated steps that is the monochlorinated disilane was formed initially until 2.1 F/mol of PhMeSiCl2 had been consumed (Equations 11, Figure 4). 

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