Si-Fluoro substituted quasisilatranes (N → Si) FYSi(OCH2CH2)2NR

The reaction of fluorosilanes XYSiF2 (X = Y = F; X = F, Y = Ph; X = Ph, Y = Me) with diethanolamines and their O-trimethylsilyl derivatives affords novel Si-fluoro substituted quasisilatranes 3, 5 and 9. These compounds were characterized by the multinuclear NMR spectroscopy and X-ray diffraction analysis. Experimental and theoretically calculated electron density distribution functions in crystal structure of 9 have shown that the N → Si coordination bond corresponds to polar bond with pronounced ionic contribution. Calculated N → Si bond order in the compound 9 does not exceed 1/3 of the normal Si–N bond. A strong N → Si coordination bond exists in compounds 3, 5 and 9 the length of which varies in the range 1.98–2.175 Å.