Organosilicon dimers

Table XI. Liquid Surface Tensions ((Tty) of Organosilicon Dimers...

Reaction with Further Electrophiles of Group IVA (Sl,Ge,Sn). IV-Silylated aziridines can be prepared from ethyleneimine by amination of chlorosilanes in the presence of an HC1 acceptor, by dehydrocondensation with an organosilicon hydride or by cleavage of a silicon—carbon bond in 2-furyl-, 2-thienyl-, benzyl-, or allylsilanes in the presence of an alkali metal catalyst (262—266). N-Silylated aziridines can react with carboxylic anhydrides to give acylated aziridines, eg, A/-acetylaziridine [460-07-1] in high yields (267). At high temperatures, A/-silylaziridines can be dimerized to piperazines (268). Aldehydes can be inserted... 

Some of the reactions given in the sections above are important routes to reactive organosilicon intermediates such as silenes and silylenes, and because of their tendency to dimerize readily, to disilenes, the latter being formed when matrix-isolated silylenes are warmed up. It appears worthwhile to summarize some of the more useful reactions leading to silenes and silylenes, and their subsequent behaviors. The topics of silylenes97,142 and disilenes97,142,143 have recently been reviewed. 

In 1981, West et al. synthesized the first stable disilene 1 via the dimerization of the corresponding silylene generated by the photolysis of a trisilane and characterized the structure by conventional spectroscopies [Eq. (2)].5 Availability of 1 and other stable disilenes has stimulated theoretical and experimental studies of various aspects of disilenes such as their bonding and structure, spectroscopic properties, reactivities, applications to the synthesis of novel types of organosilicon compounds, etc. 

The reaction of metal carbonyl dimers with silicon hydrides also probably involves an initial oxidative addition step. Chiral silyl-cobalt and silyl-manganese carbonyl complexes have been obtained through the reaction of optically active organosilicon hydrides with metal carbonyls65 68 (equation 15 and 16). Phosphine-substituted cobalt complexes were similarly obtained by reaction of a chiral hydrosilane with Co2(CO)6L2 [L = PPh3, P(OPh)3, P(c-C6Hn)3]69. 

The photolysis of cyclic trisilanes constitutes an important source of disilenes, one of the newly accessible and exciting classes of organosilicon compounds (the other major source is from the dimerization of arylsilylenes, usually derived from the photolysis of linear trisilanes). The chemistry of cyclotrisilanes has recently been reviewed7. All cyclotrisilanes studied to date yield a disilene and a silylene when photolyzed at 254 nm64"72 (equation 42). 

Komatsu K, Murata Y, Fujiwara K, Suzuki M, Murata M. Synthesis of new fullerene dimers and open-cage fullerenes by solid-state and liquid-phase reaction of Cgo with N-containing aromatics and with organosilicon compounds. Electrochem Soc Proc 2002 12 291-7. 

The method of refractometric control of the diffusate gradient in a cylinder selfoc has been worked out [102]. For the matrix (M), organosilicon dimethacrylate or DEGBAC is taken, and 4FMA is used as diffusate (D) (Table 3). Calculation of n and spatial distribution of the diffusate concentration with respect to the selfoc radius is based on the supposition that the selfoc consists of a copolymer network of substances M and D only. Such a network consisting of monomeric units M and D can be represented (in the calculated model system) by a random alternation of dimers M-M and M-D as repeated units of copolymers. For such polymer network ... 

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