SYNTHESIS OF AMINEFUNCTIONALISED AND CHLO ROFUNCTIONALISED CYCLOTRISILOXANES WITH THE AUXILIARY REAGENT HEXAETHYLDISTANNOXANE

The interaction of cyclodisilazandichloro compound 1 with hexaethyldis tannoxane 2 first leads at room temperature to the substitution of one chlorine atom by a triethylstannoxane group. At higher temperature, t he second chlorine atom is also replaced by a stannoxane group. The re action of 1 with two equivalents of 2 results in the distannoxanebis(a mino)silane 4 and is carried out without solvent so that the formed ch lortriethylstannane can be removed easily under reduced pressure after completion of the reaction. By treatment of 1,3-dichloro-1,1,3,3-tetr amethyl-disiloxane 5 and 1,1,1,3,3,3-hexachlor-disiloxane 6 with the s ilyldistannoxane compound 4 the cyclotrisiloxanes 7 and 8 are obtained . In addition to the common characterisation methods, 7 and 8 have als o been subject to single crystal X-ray analyses revealing two similar almost planar Si3O3 six membered cycles. The mean Si-O bond lengths wi thin the cycles [Si-O 1.632(13) (7) and 1.619(22) Angstrom (8)] are a function of the different electronegativities of the silicon substitue nts.