Intermolecular triple proton and deuteron transfer in crystalline 3,5-dimethylpyrazole studied by NMR, NQR, and x-ray methods

Journal Article · Wed Sep 13 04:00:00 EDT 1989 · Journal of the American Chemical Society; (USA)

OSTI ID:6724815

Wehrle, B; Aguilar-Parrilla, F; Limbach, H H ^[1]; Cano, F H ^[2]; Elguero, J ^[3]; Baldy, A; Pierrot, M ^[4]; Khurshid, M M.T.; Larcombe-McDouall, J B; Smith, J A.S. ^[5]

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1. Universitaet Freiburg (West Germany)
2. Instituto Rocasaolano, Madrid (Spain)
3. C.S.I.C., Madrid (Spain)
4. Universite Aix-Marseille III (France)
5. King's College, London (England)

A combination of {sup 13}C, {sup 15}N magnetic resonance, {sup 14}N quadrupole double resonance, and x-ray studies of solid 3,5-dimethylpyrazole between 270 and 350 K has shown that the NH...N hydrogen bond units present in the crystal are dynamically disordered, so that each nitrogen atom is on average attached to half a hydrogen atom. The molecules form discrete hydrogen-bonded cyclic trimers, in which the hydrogen atoms move in a double minimum potential energy surface which is symmetrical, to within experimental error. The experimental evidence in this temperature range is consistent with disorder by means of correlated triple hydrogen jumps with an activation energy of 45 kJ mol{sup {minus}1}. There is a large kinetic hydrogen (HHH)/deuterium (DDD) isotope effort of >20 at 299 K and equal to 8 at 347 K.

• OSTI ID: 6724815
• Journal Information: Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 111:19; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AZOLES
CALCULATION METHODS
CHEMICAL BONDS
CRYSTAL STRUCTURE
DATA
DATA ANALYSIS
DEUTERON PROBES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROGEN TRANSFER
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PROBES
PYRAZOLES