THALLIUM-STABILIZED SILSESQUIOXIDES - VERSATILE REAGENTS FOR THE SYNTHESIS OF METALLASILSESQUIOXANES, INCLUDING HIGH-VALENT MOLYBDENUM-CONTAINING SILSESQUIOXANES

The reactions of the incompletely-condensed silsesquioxanes (c-C6H11)(7)Si7O9(OH)(3) (1a), (c-C6H11)(7)Si7O9(OTMS)(OH)(2) (2a), (c-C5H9)(7)Si7O9(OTMS)(OH)(2) (2b), and (c-C6H11)(7)Si7O9(OTMS)(2)(OH) (3a) with thallium(I) ethoxide (1/1 Tl/OH) result in the formation of the corresponding Tl-substituted silsesquioxanes [(C-C6H11)(7)Si7O9(OTl)(3)](n) (7a), [(c-C6H11)(7)Si7O9(OTMS)(OTl)(2)](n), (8a), [(c-C5H9)(7)Si7O9(OTMS)(OTl)(2)](n) (8b), and [(c-C6H11)(7)Si7O9(OTMS)(2)(OTl)](n) (9a). These thallium-stabilized silsesquioxides are not prone to cycloelimination reactions or the formation of ''ate'' complexes. They are versatile anionic equivalents of incompletely condensed silsesquioxanes which react- with a variety of halide complexes, including POCl3 and MoO2Cl2, to afford high yields of metallasilsesquioxanes.