Conformational Control of Polysilanes: Use of CH2 Spacers in the Silicon Backbone
By the reaction of a number of oligosilyl potassium compounds with (trimethylsilyl)chloromethane, derivatives containing the (trimethylsilyl)methyl substituent were prepared. Using X-ray single-crystal structure analysis and UV spectroscopy the conformational properties of some of the compounds were studied. It was found that the (trimethylsilyl)methylated examples exhibit UV absorption properties which correspond to lower energy transitions in comparison to those of analogous trimethylsilylated molecules. The influence of this effect decreases, however, with increasing chain lengths.
Electron Transfer and Modification of Oligosilanylsilatranes and Related Derivatives
Several silatranyl -substituted oligosilanes were prepared starting from bis(trimethylsilyl)silatranylsilanide. Electrochemical and theoretical investigations of some oligosilanes revealed that electrooxidation occurs by formation of a short-lived cation radical. This species undergoes structural relaxation to form a pair of conformers, with endo and exo relationships with respect to the Si–N interaction. Reaction of a 1,4-disilatranyl-1,4-disilanide with 1,2-dichlorotetramethyldisilane gave a mixture of cis and trans diastereomers of a cyclohexasilane with the trans isomer showing a diminished Si–N distance.
Preparation and characterization of tris(trimethylsilyl)silyl derivatives of tin. X-ray crystal structure of Cl2Sn[Si(Si(CH3)3)3]2
Six new [tris(trimethylsilyl)silyl]tin(IV) compounds, R 4-x Sn[Si(SiMe 3 ) 3 ] x (R = Me, x = 1, 2; R = n-Bu, x = 1, 2; R = Cl, x = 1, 2) have been prepared and characterized, including 1 H, 13 C, 29 Si, and 119 Sn NMR spectra, which were consistent with the expected structures. An X-ray structure determination of Cl 2 Sn[Si(SiMe 3 ) 3 ] 2 revealed a pronounced distortion of the tetrahedral geometry around tin induced by the large steric requirements of the Si(SiMe 3 ) 3 groups. Crystals of C 18 H 54 Cl 2 Si 8 Sn were monoclinic, C2/c