Host-guest chemistry. The structure and proton disorder of the three-component crystal formed by 3(5)-methyl-4-nitropyrazole, (R, R)-(−)-trans-4,5-bis (hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane and toluene
✍ Scribed by F. Toda; K. Tanaka; C. Foces-Foces; L. Infantes; R. M. Claramunt; C. López; J. Elguero
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 411 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0894-3230
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✦ Synopsis
The crystal structure at 200 K of the complex formed by the optically active host (R,R)-(-)-trans-4,5bis(hydroxydiphenylmethyl)-2,2-dimethyl-l,3-dioxolane ( 2 ) and 4-nitro-5-methylpyrazole (lb) and toluene as guests was determined by x-ray analysis. Although only the NH protons corresponding to tautomer l b were found in the structure, some anomalies in the bond angles involving the nitrogen atoms of the pyrazole ring suggested the presence of about 25% of a structure containing the 3-methyl-4-nitropyrazole tautomer (la). This hypothesis was confirmed by '-'C cross polarization magic angle spinning NMR spectroscopy.