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Gas‐phase (ion cyclotron resonance spectrometric) and solid‐state (crystallographic) studies of highly substituted pyrazoles
Author(s) -
Abboud JoseLuis M.,
FocesFoces Concepcion,
Herreros Marta,
Homan Hamid,
Infantes Lourdes,
Notario Rafael,
Krebs Adolf W.,
Neubauer Jörg,
Elguero José,
Jagerovic Nadine
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(199602)9:2<79::aid-poc756>3.0.co;2-7
Subject(s) - chemistry , fourier transform ion cyclotron resonance , pyrazole , molecule , steric effects , ion cyclotron resonance , crystallography , ion , planarity testing , nuclear quadrupole resonance , atom (system on chip) , resonance (particle physics) , computational chemistry , stereochemistry , nuclear magnetic resonance , cyclotron , organic chemistry , atomic physics , physics , computer science , embedded system
The gas‐phase basicities of 3,4,5‐tri‐ tert ‐butylpyrazole (I) and 1,3,4,5‐tetra‐ tert ‐butyl‐pyrazole (II) were measured by Fourier transform ion cyclotron resonance spectrometry. The x‐ray molecular structures of I·HCl (a monohydrate) and II were determined. A clear lack of planarity is present in the pyrazole rings because of the steric effects of the tert ‐butyl substituents. The C sp 3atom bonded to N‐1, C‐3, C‐4 and C‐5 atoms deviates significantly from the pyrazole plane, as expected on the basis of semi‐empirical AM1 calculations. In I·HCl, the molecules form dimers through symmetry centres in which the chlorine atom and the water molecules play an important role.