Pyridines



 

 









Nitrogen


Nuclear Quadrupole Coupling Constants


in Substituted Pyridines


 








 

 





 








Collected here are the results of calculation of the pyridinic nitrogen nqcc's on B3P86/ 6-31G(3d,3p) optimized molecular structures of a number of substituted pyridines.
 

 








In the following Tables, Xzz (MHz) is the principal value of the nqcc tensor,
ETA = (Xxx - Xyy)/Xzz, and Øz,bi (degrees) is the angle between the z-principal axis and the bisector of the CNC angle.
 








 









 
Table 1. Pyridinic nitrogen nqcc's in mono-substituted pyridine, normal species.
 
  Xzz ETA Øz,bi
 
Pyridine -4.915 0.416    0
 
2-Monofluoro- -4.466 0.249 0.44
3- -4.997 0.404 1.24
4- -4.761 0.332    0
 
2-Monochloro- -4.728 0.274 0.17
3- -4.928 0.408 1.09
4- -4.839 0.373    0
 
2-Monobromo- -4.779 0.279 0.69
3- -4.905 0.409 1.23
4- -4.859 0.386    0
 
2-Monomethyl- -4. 755 0.349 0.57
3- -4.929 0.425 0.10
4- -4.783 0.383 0.24
 
2-Cyano- -5.001 0.368 2.13
3- -4.954 0.401 0.35
4- -5.064 0.448    0
 
2-Carbaldehyde -4.913 0.456 0.97
3- -4.923 0.395 0.08
4- -5.119 0.466 0.08
 


   








  








 







 
Table 2. Pyridinic nitrogen nqcc's in di-substituted pyridine, normal species.
 
  Xzz ETA Øz,bi
 
Pyridine -4.915 0.416    0
 
2,3-Difluoro- -4.498 0.251 0.51
2,4- -4.306 0.157 0.48
2,5- -4.539 0.239 1.53
2,6- -4.049 0.063    0
3,4- -4.831 0.321 1.31
3,5- -5.041 0.401    0
 
2,3-Dichloro- -4.734 0.268 1.41
2,4- -4.642 0.228 0.17
2,5- -4.743 0.269 1.14
2,6- -4.543 0.125    0
3,4- -4.841 0.371 1.00
3,5- -4. 918 0.405    0
 
2-Cl-3-F- -4.764 0.273 0.98
2-F-3-Cl- -4.462 0.243 0.85
2-Cl-4-F- -4.568 0.187 0.12
2-F-4-Cl- -4.375 0.202 0.43
2-Cl-5-F- -4.807 0.267 1.25
2-F-5-Cl- -4.481 0.243 1.40
2-Cl-6-F- -4.297 0.094 0.21
3-Cl-4-F- -4.772 0.329 1.00
3-F-4-Cl- -4.913 0.346 1.16
3-Cl-5-F- -4.981 0.402 0.14
 
2,6-Dimethyl -4.590 0.278    0
 
2,6-Dicyano -5.074 0.324    0
 
 
 
 
 
Table 3. Pyridinic nitrogen nqcc's in penta-substituted pyridine, normal species.
 
  Xzz ETA Øz,bi
 
Pyridine -4.915 0.416    0
 
Pentafluoro- -3.878 0.040    0
 
Pentachloro- -4.433 0.080    0
 
 
  
 

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Last modified 16 Feb 2004