High-Nuclearity (Cu₈-Based) Cage Silsesquioxanes: Synthesis and Structural Study

We herein report a study of Cu(II)-silsesquioxanes' self-assembly in the presence of two possible template agents (acetonitrile and acetone). This results in the isolation of unusual high-nuclearity cluster Cu^II ₈ cage silsesquioxanes [(Ph₈Si₈O₁₆)₂Cu₈(DMF)₈][Ph₈Si₈O₁₂]·2MeCN 1 and [(Me₈Si₈O₁₆)₂Cu₈(Me₂CO)₄]₂[MeCOO^-]₂[Na⁺]₂·2(H₂O)·3(Me₂CO) 2. In the case of 1, acetonitrile indeed serves as a template being incorporated into the inner void of the prism-like cage of the crystalline product. To the contrary, in the case of complex 2, acetone molecules just play the role of external solvates. An inner void of the prism-like cage in 2 is occupied by sodium acetate groups. The latter, most likely, are produced via the mild oxidation of ethanol during the synthesis of 2. Finally, the sodium centers of these acetate groups caused an unprecedented "cage connectivity" (dimerization of two octacopper cage silsesquioxanes in 2).