Functionalized disilenes

As a functional disilene, Wiberg synthesized a halogen-substituted disilene. Treatment of trihalosilane 85 in pentane with a THF solution of tri(7< r/-butyl) silylsodium gives (E)-1,2-dichloro-1,2-disilyldisilene 42 in about 12% yield 22... 

Ab initio calculations reproduce the experimentally observed geometrical changes. Ethylene is planar (absolute true minimum global minimum) at all theoretical levels. The computed geometry of disilene depends strongly on the basis functions and on electron... 

Another innovative route to polysilanes involves the anionic polymerisation of disilabicyclooctadienes 10.9, which function as sources of masked disilenes, e.. Me2Si=SiMe Bu [eqn (10.10)]. ... 

It is clear that introduction of the functional groups to the silicon-silicon double bond causes a large red shift of the absorption maxima of disilenes. Similar substituent effects have been known for a variety of alkenes31. Qualitatively, the reason for the red shift should arise from destabilization of the HOMO of the disilene by an appreciable interaction between the n-orbital of the heteroatoms and the tr-orbital of the disilene, although the effect of their distorted structure should also be considered as discussed later. 

Polyphenylsilane, (PhSiH) , can be derivatized by free-radical hydrosilylation in the presence of a radical initiator. Alkenes, ketones and aldehydes react readily, to replace up to 93% of the Si-H bonds. This route can be employed to make polysilanes with hydrophilic groups, such as hydroxy, amino and carboxylic acid functions.43 Dialkylamino substituted polysilanes, made by the anionic polymerization of masked disilenes (see equation (17)), when treated with acetyl chloride give chloro-substituted poly silanes. The chlorine can then be displaced by other nucleophiles.27... 

Optimization of the latter reaction is an object of current study.26 Electrosynthesis of polysilanes has undergone a transformation from laboratory research experiments27-32 to industrial production of imaging polysilanes for microlithography.33 Anionic polymerization of masked disilenes was established as a new synthetic route to polysilanes of highly ordered structure.34 A functional polysilane with an ethereal group, poly[l-(6-methoxy-hexyl)-1,2,3-trimethyldisilanylene] (Mn = 7.2 X 103) was prepared by the mask disilene method.35... 

Most of the work done so far on the mechanism of alcohol additions to disilenes has been carried out with the kinetically stabilized derivatives ( )-92a151-153, ( )- and (Z)-92b152 and tetramesityldisilene (110)151,153 154. These compounds react with alcohols some 109 —1012 times more slowly than do the transient disilenes 103 and 104 and, as was shown specifically for 110, the rates vary more dramatically as a function of alcohol structure153. 

Regiospedfic Polymerization of Masked (Dibutylamino)(trimethyl)disilene and Functional Transformation... 

Anionic polymerization of masked disilenes presents exciting opportunities for the synthesis of polysilanes of well-defined structure and functionality [7, 8]. Indeed, we have found that amino-substituted masked disilenes could be prepared and polymerized successfully to unprecedented amino-substituted polysilanes with a completely head-to-tail structure, poly[ 1,1,2-trimethyl-2-(dibutylamino)disilene]s [9]. 

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