Fluoride complexation by bidentate silicon Lewis acids

Abstract

Diethynyldiphenylsilane (1) and divinyldiphenylsilane (2) were functionalized by hydrosilylation reactions with HSiMe₂Cl, HSiMeCl₂ and HSiCl₃. Fluorination of the resulting compounds generates bidentate open-chain Lewis acids of increasing acidity. All semi-flexible [Ph₂Si(CHCHSiF_nMe_3−n)₂ (n = 1, 2, 3)] and flexible [Ph₂Si(CH₂–CH₂SiF_nMe_3−n)₂ (n = 1, 2, 3)] bidentate Lewis acids were obtained in good to excellent yields. The different fluoride ion complexation behavior was explored in detail by multinuclear (low temperature) NMR spectroscopy. The Lewis acidic bidentate molecules as well as the resulting mono- and bissilicates were completely characterized by NMR spectroscopy, mass spectrometry and in part by elemental analysis and X-ray diffraction experiments.