Beiträge zur Chemie der Silicium-Schwefelverbindungen. XXXVIII. Hexa-(tri-t-butoxy)disiloxan und Hexa-(tri-t-butoxy)disilthian

Contributions to the Chemistry of Silicon Sulfur Compounds. XXXVIII. Hexa(tri-t-butoxy)disiloxane and Hexa(tri-t-butoxy)disilthiane Hexa(tri-t-butoxy)disiloxane 1 and Hexa(tri-t-butoxy)disilthiane 2 were prepared by reaction of R₃SiONa with R₃SiCl and R₃SiSNa with R₃SiCl (R = tri-t-butoxy), respectively. The mass spectra show characteristic series of fragments. A large ²⁹Si n.m.r. chemical shift of about —103.55 ppm is observed with 1 , whereas the value of 2 is —75.99 ppm. The crystal structure analysis of 1 result first in a colinear molecule (Si? ;O? ;Si = 180°) with 1 symmetry and relative short mean bond lengths of about d(Si? ;O) = 155.6 pm, but with large and strong anisotropic ellipsoids. Their quantitative rigid body analyses yield decisive corrections, namely a bent molecule with an Si? ;O? ;Si angle of 144.0° and d?_corr = 163.5 pm. Molecule 2 is also bent as expected (Si? ;S? ;Si = 110.5°, d?(Si? ;S) = 211.9 pm and after rigid body correction 108.0° and d_corr = 215.2 pm, respectively). The results of our investigations will be discussed corresponding to the energy differences of the varying configurations at the bridging atoms.