1-t-Butyl-1-phenyl-1-silacyclohexane: Synthesis, conformational analysis in gas and solution by GED, FT-IR and theoretical calculations

Abstract

1-t-Butyl-1-phenyl-1-silacyclohexane 1, the first disubstituted silacyclohexane with the most bulky substituent, t-Bu group, at silicon, was synthesized via the sequence of reactions PhSiCl3 → Ph(Cl)Si(CH2)5 → Ph(t-Bu)Si(CH2)5, and its molecular structure and conformational preferences were studied by gas-phase electron diffraction (GED), temperature variable IR spectroscopy and quantum chemical calculations of the isolated conformers and their solvate complexes in gas and in polar medium. The predominance of the t-Bueq conformer in gas phase (1-Phax:1-Pheq = 92:8, ΔG° = 1.63 kcal/mol) determined from GED is consistent with the results of quantum chemical calculations at the DFT and MP2 level of theory.