Molecular structure and conformational analysis of 3-methyl-3-silathiane by gas phase electron diffraction, FTIR spectroscopy and quantum chemical calculations

Synthesis and Conformational Analysis of 3-Methyl-3-silatetrahydropyran by GED, FTIR, NMR, and Theoretical Calculations: Comparative Analysis of 1-Hetero-3-methyl-3-silacyclohexanes

“…26 The methyl group is the reference substituent in conformational analysis (actually, it is common to adjust the effects of all other substituents with that of the methyl group). Inasmuch as the conformational analysis was already performed for 1methylsilacyclohexane, 21,23 1,3-dimethyl-3-silapiperidine, 27 and 3-methyl-3-silathiane (Scheme 1), 28,29 the only missing link in the series of the studied silaheterocyclohexanes is 3-methyl-3silatetrahydropyran 1. The corresponding study will throw light on the anomeric (homoanomeric) effect in sila(hetero)cyclohexanes.…”

“…23,25,26 For 1-SiH 3 -1-silacyclohexane, the axial preference in the gas phase is reversed to the equatorial preference in solution. 22 1,3-Dimethyl-3-silapiperidine 27 and 3-methyl-3-silathiane 28,29 show an explicit inversion of conformational preferences from the predominant axial conformer in the gas phase to the predominant equatorial conformer in solution. This motivated the second goal of our study, which was to analyze the dependence of conformational preferences of the methyl group on the nature of the second heteroatom in silaheterocyclohexanes.…”

Conformational Preferences of the Phenyl Group in 1-Phenyl-1-X-1-silacyclo-hexanes (X = MeO, HO) and 3-Phenyl-3-X-3-silatetrahydropyrans (X = HO, H) by Low Temperature 13C NMR Spectroscopy and Theoretical Calculations

“…While for the former all methods predict complete predominance of the Ph ax conformer, for the later the Ph ax conformer predominates at room temperature or in gas phase but at low temperature in solution the Ph eq conformer is preferable both as an isolated molecule and as a complex with CHCl 3 . Opposite conformational preferences in gas phase and in solution for sila­(hetero)­cyclohexanes were clearly demonstrated in a number of our works, ,,,,− It deserves special mentioning that for the Si–Ph-containing compounds there is a general trend of predominance of Ph ax conformers in the gas phase and of Ph eq in solution. ,, Therefore, the results for 3-OH and 3-OMe 3-phenyltetrahydropyrans 3 , 4 and 8 in Table are in compliance with this trend.…”

Conformational properties of 1-cyano-1-silacyclohexane, C5H10SiHCN: Gas electron diffraction, low-temperature NMR and quantum chemical calculations

“…Whereas a solvation effect, possibly related to the polarity of the cyano group, we note that continuum solvation calculations, by using both the COSMO 43 and SMD 44 solvation models (implicit solvation models), were carried out separately at the B3LYP give positive A values both in gas-phase and in solutions. In this context, however, it is notable that some 1-methyl-3-hetero(X)-1-silacyclohexanes (X = NMe, 56 O, 57 and S 58,59 ) also show Me-axial preferences in the gas-phase (GED) but Me-equatorial preferences by DNMR in solutions.…”