Crystal structures and theoretical calculations of trans-2,4,4-trimethyl-4-silathiane 1-oxide and 4,4-dimethyl-4-silathiane 1,1-dioxide

Abstract

The crystal and molecular structures of trans-2,4,4-trimethyl-4-silathiane 1-oxide 1 and 4,4-dimethyl-4-silathiane 1,1-dioxide 2 were determined by single crystal X-ray diffraction. Both compounds have the chair conformation with the 2-Me and the S=O group in compound 1 occupying the equatorial positions. The DFT (B3LYP/6-311G(d,p)) and MP2 (MP2/6-311G(d,p)) theoretical calculations nicely reproduce the X-ray experimental geometry. The obtained results are discussed in connection with the electronic and structural properties of the compounds.

Silacyclohexanes, Sila(hetero)cyclohexanes and Related Compounds: Structure and Conformational Analysis

“…As to the ring conformation, an important difference is a smaller angle of folding between the C2C3C5C6 plane of the ring and the C2SiC6 plane with respect to the C3C4C5 plane as depicted in Figure 1. The same is true for the nitrogen, oxygen or sulfur-containing heterocycles, in which atom C4 is replaced by the corresponding heteroatom [4]. The three main issues in conformational analysis of cyclohexanes and all their derivatives are the ring conformation, the ratio of the conformers, and the barrier to their interconversion.…”

“…We know only one example of the S=O•••Si coordination in which the trigonal bipyramidal structure was proved experimentally [51]. 4-Silathiane S-sulfimides, which are isoelectronic analogues of 4-silathiane S-oxides ( Figure 7), also have very low activation barriers from 4.4 to 4.7 kcal/mol [52]. For N-phenylsulfonyl-4-silathiane S-sulfimide ( Figure 7) the conformational equilibrium is almost degenerate (1:1), whereas in N-triflyl-4-silathiane S-sulfimide the equilibrium is shifted to the axial conformer (~55:45) due to electronegative CF 3 group [52].…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 19, 2008) and the discipline

“…In the following paper, Shainyan et al [284] used single crystal X-ray diffraction to determine the crystal and molecular structures of trans-2,4,4-trimethyl-4-silathiane 1-oxide and 4,4-dimethyl-4-silathiane 1,1-dioxide. Previously, the authors had used NMR spectroscopy to theoretically and experimentally investigate these two compounds and their desire was to obtain direct evidence to confirm their proposed structures.…”

Conformational analysis of 4,4‐dimethyl‐4‐silathiane and its S‐oxides

“…The 4,4‐dimethyl‐4‐silathiane 1‐oxide and its mono and dimethyl derivatives have been studied by NMR and theoretical calculations 26. For 2,4,4‐trimethyl‐4‐silathiane S‐oxide the X‐ray structure was obtained 27. 4‐Silathiane S‐oxides having one or two halogen atoms in different combinations at silicon were studied theoretically in a search for the transannular SO … Si bonding 15–19.…”

“…4‐Silathiane S‐oxides having one or two halogen atoms in different combinations at silicon were studied theoretically in a search for the transannular SO … Si bonding 15–19. As to the corresponding sulfones, only 4,4‐dimethyl‐4‐silathiane S,S‐dioxide was studied by us using room‐temperature NMR spectroscopy26 and X‐ray analysis 27. In continuation of our studies of the stereochemistry of 1,4‐thiasilacyclohexanes (4‐silathianes) and their S‐oxides15–19, 26, 27 we report in the present work the conformational analysis of 4,4‐dimethyl‐4‐silathiane ( 1 ), 4,4‐dimethyl‐4‐silathiane S‐oxide ( 2 ), and 4,4‐dimethyl‐4‐silathiane S,S‐dioxide ( 3 ), as depicted in Scheme , in the established combined manner of low temperature NMR spectroscopy and theoretical calculations.…”