Heptanuclear Cage CuII-Silsesquioxanes: Synthesis, Structure and Catalytic Activity

Two prismatic phenyl- (PhSiO1.5)14(CuO)7 (1, 29 % yield) and methyl- (MeSiO1.5)14(CuO)7 (2, 19 % yield) heptacoppersilsesquioxanes were obtained by the interaction of Cu,Na-based cage silsesquioxanes [(RSiO1.5)12(CuO)4(NaO0.5)4] (R = Ph, Me) with 4,4′-bipyridine and pyrazine, respectively, acting as “silent witness” ligands. Unusual molecular topologies of both compounds 1 and 2, which are the first representatives of cage silsesquioxanes with seven metal ions in their cores, were established by X-ray diffraction studies. Complex 1 was found to be an active precatalyst in the oxidation of alkanes and 1-phenylethanol to alkyl hydroperoxides and acetophenone, respectively. Alkanes were oxidized by hydrogen peroxide, and the alcohol was oxidized by tert-butyl hydroperoxide. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim