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The Unusual Properties of 5‐Methyl‐4,5,6,7‐Tetrahydro‐1H‐Indazole in the Solid State
Author(s) -
FocesFoces Concepción,
Hager Orm,
Jagerovic Nadine,
Jimeno María Luisa,
Elguero José
Publication year - 1997
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19970030119
Subject(s) - tautomer , trimer , chemistry , hydrogen bond , indazole , proton , molecule , crystal structure , crystallography , solid state , stereochemistry , computational chemistry , organic chemistry , physics , dimer , quantum mechanics
The crystal structure of the title compound was determined by X‐ray analysis at 200 K. Three independent molecules form a trimer joined by strong and linear N‐H … N hydrogen bonds. There is another centrosymmetrically related trimer in the unit cell. Both tautomers (1 H and 2 H ) are present in each trimer. Disorder of the N H protons involved in the N‐H … N hydrogen bonds has been observed. Solid‐state 13 C CPMAS NMR was used to establish the dynamic nature of the N H ‐proton disorder, the title compound being the first example of proton transfer in a tautomeric mixture of pyrazoles with an equilibrium constant other than 1.