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A variety of 9-phospha-10-silatriptycenes (PSiT) and some derivatives, such as the phosphine selenides and cis-platinum complexes, have been prepared in order to study their structures and characteristics as a phosphine ligand. The 1 J(P−Se) NMR coupling constant of the phosphine selenides demonstrate the large s character of the lone pair orbital on the phosphorus atom, attributable to the small C−P−C bond angles of the PSiT framework, as confirmed by X-ray crystallography. The strong trans influence of PSiT has been determined from the 1 J(Pt−C) coupling constant measurements of the cis-[PtMe2(psit)2], which is due to the increase in the P−Pt−P angle in the complexes derived from the steric repulsion between the two bulky PSiT ligands. Both the substituent on the silicon and the bridging benzene rings affect the electronic character. Electron-withdrawing substituents on the silicon atom slightly increase the s character of the phosphorus lone pair orbital, and the isopropoxy groups on the bridging benzene rings increase the trans influence.

o-(Fluorosilyl)(dimesitylboryl)benzenes have been prepared as colorless crystals by reacting fluorodimesitylborane with o-(fluorodimethylsilyl)phenyllithium and o-(fluorodiphenylsilyl)phenyllithium. The o-(fluorosilyl)(dimesitylboryl)benzenes serve as B/Si bidentate Lewis acid and efficiently capture fluoride ion 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. Fluoride ion affinities of the o-(fluorosilyl)(dimesitylboryl)benzenes were evaluated in comparison with non-silylated triarylborane.