A new route to incompletely-condensed silsesquioxanes: base-mediated cleavage of polyhedral oligosilsesquioxanes

Abstract

Readily available R₈Si₈O₁₂ frameworks react selectively with aqueous Et₄NOH to afford discrete incompletely-condensed silsesquioxanes: reaction of R₈Si₈O₁₂ (2a, R = c-C₆H₁₁; 2b, R = Buⁱ) with Et₄NOH first produces endo-D₂-R₈Si₈O₁₁(OH)₂ (3a, R = c-C₆H₁₁; 3b, R = Buⁱ), which reacts further with Et₄NOH to produce endo-C₂-R₈Si₈O₁₀(OH)₄ (5a and 5b) and endo-C₃-R₇Si₇O₉(OH)₃ (4a, R = c-C₆H₁₁; 4b, R = Buⁱ); the reactions of Et₄NOH with Me₈Si₈O₁₂ (2c), (c-C₆H₁₁)₇(H)Si₈O₁₂ (2d) and (c-C₆H₁₁)₇(OH)Si₈O₁₂ (2d) also produce the corresponding trisilanols (i.e. endo-C₃-R₇Si₇O₉(OH)₃ (4a, R = c-C₆H₁₁; 4c, R = Me).