Synthesis and structural characterization of a remarkably stable, anionic, incompletely condensed silsesquioxane framework

Abstract

The reaction of [(C₆H₁₁)₇Si₇O₉(OH) ₃] 1 (2 equiv.) with [(C₆H₁₁)₇Si₇O₉(OTl )₃] 3 affords a conproportionation product that reacts with [PPh₄]Cl, [PBuⁿ₄]Cl and [NBuⁿ₄]Br to produce the corresponding salts of [(C₆H₁₁)₇Si₇O₁₀(OH )₂]^- 5 (i.e. the monoanion derived from deprotonation of 1); a single-crystal X-ray diffraction study of the [(NBuⁿ₄]⁺ salt of 5 indicates that the molecules exist as isolated ion pairs with strong intramolecular hydrogen bonding; implications of this result for the chemistry of silica are discussed.

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