Alkenyl-Functionalized Open-Cage Silsesquioxanes (RSiMe(2)O)(3)R′(7)Si(7)O(9): A Novel Class of Building Nanoblocks

[Image: see text] Trifunctional incompletely condensed polyhedral oligomeric silsesquioxanes (RSiMe(2)O)(3)R′(7)Si(7)O(9) (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 (HSiMe(2)O)(3)R′(7)Si(7)O(9) (R′ = i-C(4)H(9) (1a), (H(3)C)(3)CH(2)C(H(3)C)HCH(2)C (1b)). The resulting products are synthetic intermediates that contain C=C bonds and functional groups (e.g., OSiMe(3), SiR(3), Br, F, B(O(C(CH(3))(2))(2) (Bpin)), thienyl), which make them suitable for application in the synthesis of novel, complex, hybrid materials with unique properties.