CAGE-REARRANGEMENT OF SILSESQUIOXANES

Deca- and dodeca-silsesquioxane cages were prepared by partial rearran gement of octa-silsesquioxanes, R-8(SiO1.5)(8) (I), to give species of the type R-10(SiO1.5)(10) (II) and D-2d-R-12(SiO1.5)(12) (III). This rearrangement is catalysed by sodium acetate, sodium cyanate, sodium s ulfite, sodium hydroxide and potassium carbonate in acetone as solvent . The mixture of [Cl-(CH2)(3)](8)(SiO1.5)(8) (Ic), [Cl-(CH2)(3)](10)(S iO1.5)(10) (IIc) and D-2d-[Cl-(CH2)(3)](12)-(SiO1.5)(12) (IIIc) can be separated by NP-HPLC. The reaction was also studied in acetonitrile u sing sodium fluoride, sodium or potassium hexafluorosilicate and 18-cr own-6 as catalysts. Simultaneous reaction of (Ic) and [NCS-(CH2)(3)](8 )(SiO1.5)(8) (If) with sodium acetate in acetone leads to a mixture of octa-, deca- and dodeca-silsesquioxanes with a statistical distributi on of the Cl(CH2)(3)- and NCS(CH2)(3)-side groups. The Si-29 NMR data of the synthesized silsesquioxanes have been collected. The shift data can be calculated following simple additivity rules. (C) 1997 Elsevie r Science Ltd.