itylboryl)benzenes serve as B/Si bidentate Lewisacid and efficiently capture fluorideion from potassium fluoride in the presence of [2.2.2]cryptand or 18-crown-6 in toluene, giving the corresponding mu-fluoro bridged products. The structures were characterized by X-ray crystal structure analysis and multinuclear NMR spectroscopy. Fluorideionaffinities of the o-(fluorosilyl)(dimesitylboryl)benzenes