Mercurials silyl

Photolysis. The photolysis of silyl mercurials is one of the most useful methods for the production of silyl radicals ... 

As an alternative to condensation of dichlorosilanes by alkali metals, it is possible to synthesize poly silanes by the reaction of preformed dilithio compounds with dichlorosilanes. An early synthesis of a copolymer by this route is illustrated in equation (19).10 (see also Section 5.9.2). Finally, poly(phenylmethylsilylene) has been made by thermal decomposition of a silyl-mercury polymer36 (equation (20)). 

Formation of Silicon-Transition and Inner Transition-Metal Bond 5.8.3.5. from Bis(silyl) Mercurials... 

Previously, trifiuorosilyl groups have been bound to phosphorus 40) and silicon via the SiF2(g), fluorine-bond insertion-mechanism 41). The new compound Hg(SiFs)2 is readily hydrolyzed, but it can be stored for long periods of time in an inert atmosphere. It is a volatile, white solid that is stable up to at least 80°C. The preparation of bis(trifluoro-silyl)mercury, of course, raises the possibility of (a) synthesis of the complete series of trifluorosilyl, "silametallic compounds, as had previously been done for bis(trifluoromethyl)mercury by using conventional syntheses, and (6) transfer reactions similar to those in Section II, as well as (c) further exploration of the metal-vapor approach. The compound Hg(SiF,)2 appears also to be a convenient source of difluoro-silane upon thermal decomposition, analogous to bis(trifluoromethyl)-mercury ... 

The fact that irradiation of disilanes la - 3a did not produce detectable products other than the corresponding silyl radicals indicates that the radicals produced photochemically undergo clean recombination to produce the starting silane, as shown in Scheme 5 path (b). An exception is the photochemical reaction of silyl mercurial compounds 4c, which produce the hydrosilane 6 [Scheme 5, path (c)], while the corresponding dimer 4a [Scheme 5, path (b)] is not detected. Apparently, for radical 4b, hydrogen abstraction to produce silane 6 occurs significantly faster than its dimerization to 4a. 

These silyl mercurials are stable over several days at RT, but as solids they react with traces of air or H2O. Organo(chloro)silylmercurials, (R Cl3 Si)2Hg (n = 0-2), also are known... 

The isolation of an optically active silyl-mercurial derivative has also been reported95 (equation 28). 

The treatment of an optically active hydrosilane with di-t-butyl mercury led to a silyl mercurial in apparently low optical purity. It is noteworthy that the silyl-mercurial derivative underwent thermal racemisation. 

Linear organomercurials provide a convenient basis for the investigation of the effect of susbstitution in the organic moiety on the metal chemical shift. Increase in the shielding of 150 ppm are observed for each substitution of Me for a H in Hg-CH3 derivatives, while smaller decreases in shielding ( 30 ppm) occur on substitution of )S-Hs. Cadmium alkyls show a similar behavior, but for silyl mercury compormds, replacements at both a and position results in deshielding. 

Arylpentafluorophenyl-iodonium Compounds (Scheme 48), Bis[tris(pentafluoro-phenyl)silyl]-mercury and -cadmium ((C4F4)3Si]aCd -t- CFa COjH - (CF3-C02)2Cd-F (C8F5)3SiH. Wasserfreie Trifluoroacetate der Hauptgnippe III [CFj-COjH-r... 

W.P. Neumann and K. Reuter Silyl Mercurials in Organic Synthesis J. Organomet. Chem. Library 7 229. 

Bis[tris(triethylgermyl)silyl] Mercury GeeHgSi CaeHeo [(Et3Ge)3Si]2Hg... 

Recent years have seen a remarkable development of the preparation, isolation, and characterization of stable silyl radicals. Among these (Me3Si)3Si has gained particular prominence as a popular reagent in organic synthesis [20-26]. In this connection related radicals have been studied to some extent. Following seminal contributions by Matsumoto and coworkers [363-365] key achievements in this development have been made by Sekiguchi and coworkers, which were reviewed only recently [8, 366, 367]. Most stable silyl radicals are trisilylated ones and are commonly prepared either from the respective hydrosilanes, from silyl mercury compounds, by oxidation of silyl anions, or by reduction of silyl halides (Scheme 33) [8]. 

The Apeloig group s most exciting work with silyl mercurials is associated with functionalized sUyl anions and will thus be treated in the respective chapter about this class of compounds. 

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