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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
Author(s) -
Toda F.,
Tanaka K.,
FocesFoces C.,
Infantes L.,
Claramunt R. M.,
López C.,
Elguero J.
Publication year - 1996
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199609)9:9<611::aid-poc821>3.0.co;2-m
Subject(s) - chemistry , tautomer , thiazole , crystal structure , pyrazole , ring (chemistry) , magic angle spinning , toluene , nuclear magnetic resonance spectroscopy , crystallography , stereochemistry , organic chemistry
The crystal structure at 200 K of the complex formed by the optically active host ( R,R )‐(−)‐ trans ‐4,5‐bis(hydroxydiphenylmethyl)‐2,2‐dimethyl‐1,3‐dioxolane (2) and 4‐nitro‐5‐methylpyrazole (1b) and toluene as guests was determined by x‐ray analysis. Although only the NH protons corresponding to tautomer 1b 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 (1a). This hypothesis was confirmed by 13 C cross polarization magic angle spinning NMR spectroscopy.