Adducts with Lewis Bases at Silicon

There are many instances of the formation of simple adducts between silicon-transition-metal compounds and Lewis bases (Table XIII), corresponding to mode 3 in Fig. 2. Compounds with SiHs groups react particularly readily, in the same way that iodosilane has long been known to form adducts such as HaSil nNMes in = 1,2) (36, 40, 84). 

Other possibilities include compounds with MesSi, MesSi2, and FsSi groups, although in the last case the reaction may be complicated by simultaneous disproportionation leading to formation of SiF4 2B, where B is a Lewis base (entry 31). The ClaSi derivative in entry 26 does not form adducts with nitrogen or phosphorus bases, although phosphines cause slow elimination of CO (cf. Section III,E,1). 

Rhenium derivatives (entries 10-12) are much less ready to form adducts than their manganese analogs (entries 6, 7, 9). Thus, the adducts in entry 10 dissociate completely at room temperature. 

Tertiary amines and phosphines have received the most attention, but the use of the strong base Me3P=CH2 should be noted, e.g. (entry 19), 

The methyl(trimethylsilyl)phosphines PMe (SiMe3)s n decrease in base strength as n decreases, until finally P(SiMes)3 does not react at all (entries 28, 29). 

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