Alkenyl-Functionalized Open-Cage Silsesquioxanes (RSiMe2O)3R'7Si7O9: A Novel Class of Building Nanoblocks.

Trifunctional incompletely condensed polyhedral oligomeric silsesquioxanes (RSiMe2O)3R'7Si7O9 (IC-POSSs) are considered as intriguing building nanoblocks dedicated to constructing highly advanced organic-inorganic molecules and polymers. Up to now, they have been mainly obtained via hydrosilylation of olefins, while the hydrosilylation of the C≡C bonds has not been studied at all, despite the enormous potential of this approach resulting from the possibility of introducing 3, 6, or even more functional groups into the IC-POSS structure. Therefore, in this work, we present a highly selective and efficient synthesis of the first example of tripodal alkenyl-functionalized IC-POSSs, obtained via platinum-catalyzed hydrosilylation of the terminal and internal alkynes, as well as symmetrically and nonsymmetrically 1,4-disubstituted buta-1,3-diynes with silsesquioxanes (HSiMe2O)3R'7Si7O9 (R' = i-C4H9 (1a), (H3C)3CH2C(H3C)HCH2C (1b)). The resulting products are synthetic intermediates that contain C═C bonds and functional groups (e.g., OSiMe3, SiR3, Br, F, B(O(C(CH3)2)2 (Bpin)), thienyl), which make them suitable for application in the synthesis of novel, complex, hybrid materials with unique properties.