An Optically Active Pentacoordinate Silicate: (+)-Bis(triethylammonium) Bis[(R,R)-tartrato(4-)]diphenyldisilicate

The title compound, 2C₆H₁₆N⁺.C₂₀H₁₄O₁₂Si₂^2-, was prepared by the reaction of (R,R)-(+)-tartaric acid with triethoxyphenylsilane and triethylamine in ethanol. The structure of this optically active pentacoordinate phenylsilicate consists of independent bis[(R,R)-tartrato]diphenyldisilicate anions and triethylammonium cations. In the crystal, the two Si atoms are five-coordinate and the geometry of each of the Si atoms is distorted from the trigonal bipyramid towards the square pyramid along the Berry pseudorotational coordinate by ca 9.8 and 8.9% respectively.

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