The Microwave Spectrum of Imidazole; Complete Structure and the Electron Distribution from Nuclear Quadrupole Coupling Tensors and Dipole Moment Orientation
Abstract
Spectra have been measured for eleven isotopic forms of imidazole, including single substitutions at each nucleus in turn. A complete r_{s}structure is obtained. The ring structure is:
N(1)C(2) = 1.364 Å, C(2)N(3) = 1.314 Å, N(3)C(4) = 1.382 Å, C(4)C(5) = 1.364 Å, C(5)N(1) = 1.377 Å, ≮N(1)C(2)N(3) = 112.0°, ≮C(2)N(3)C(4) = 104.9°, ≮N(3)C(4)C(5) = 110.7°, ≮C(4)C(5)N(1) = 105.5° and ≮C(5)N(1)C(2) = 106.9°.
The N(1)H(1) distance is 0.998 Å, while the CH distances are all very close to 1.078 Å. The bonds N(1)H(1) and C(2)H(2) lie close to the external bisectors of the respective ring angles, but C(4)H(4) and C(5)H(5) are each displaced by several degrees from these bisectors towards N(3) and N(1) respectively. The electric dipole moment is established as 3.67 (5) D from Stark effects, directed almost parallel with the line joining the nitrogen nuclei. The properties and orientations of the two ^{14}Nnuclear quadrupole tensors have been investigated, in particular through the spectra of the two mono^{14}Nimidazoles.
 Publication:

Zeitschrift Naturforschung Teil A
 Pub Date:
 December 1981
 DOI:
 10.1515/zna19811220
 Bibcode:
 1981ZNatA..36.1378C