Mass spectrometric characterization of polyhedral oligosilsesquioxanes andheterosilsesquioxanes

Silsesquioxanes constitute a diverse range of Si-O frameworks with a wide v ariety of intriguing possibilities as models for catalysis, These topologic ally interesting molecules are formed by the hydrolytic condensation of tri functional organosilanes. Heterosilsesquioxanes are formally derived by sub stitution of a main-group, transition-metal, or f-element atom for one or m ore Si atoms in a silsesquioxane. A number of silsesquioxanes and their met al-containing derivatives, metallasilsesquioxanes (SI-O-M), were characteri zed using atmospheric pressure chemical ionization (APCI) and turbo ion-spr ay (TISP) mass spectrometry, The use of n-hexane or n-hexane/ethanol (90:10 , v/v) allowed the techniques to be utilized to characterize a large number of complexes. In some cases addition of trace amounts of ammonium acetate, sodium chloride, or sodium acetate to the ethanolic portion of the solvent allowed the detection of [M + NH4](+) or [M + Na](+) ions. Copyright (C) 1 999 John Wiley & Sons, Ltd.