2-I-C5NH4

























 





 








Nitrogen and Iodine

Nuclear Quadrupole Coupling Constants


in 2-Iodopyridine


 








 








 

 





Nitrogen and iodine nqcc tensors in 2-bromopyridine were calculated on a structure given by B3P86 optimization with 6-31G(3d,3p) bases on H, C, and N, and 6-311G(3d) on I.  In Table 1, the calculated nitrogen nqcc's are given.  In Table 2, the calculated bromine nqcc's are compared with the experimental values [1].  Structure parameters are given in Table 3, atomic coordinates in Table 4, and rotational constants in Table 5.

 








In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percent of average absolute experimental nqcc).  RSD is the calibration residual standard deviation of the model for calculation of the nqcc's.

 








 








   






Table 1. Nitrogen nqcc's in 2-Iodopyridine (MHz).  Calculation was made on the B3P86 ropt structure.
   









Calc.
Expt.
   






14N Xaa - 0.017




Xbb - 3.105




Xcc
3.122




|Xab|
2.888



 







RSD
0.030 (1.3 %)



 







Xxx
1.714




Xyy
3.122




Xzz - 4.836




ETA
0.291




Øz,a
59.07




Øa,bi
57.86




Øz,bi *
  1.21



 







 








* The z-axis makes an angle of 1.21o with the external bisector ( 'bi' ) of the C(6)N(1)C(2) angle.

 








 








   






Table 2.  Iodine nqcc's in 2-Iodopyridine (MHz).  Calculation was made on the B3P86 ropt structure.
   









Calc.
Expt. [1]
   






127I Xaa -
 1873.6
 -
 1881(2)


Xbb
1022.9
1017(2)


Xcc
  850.7
  864(2)


|Xab|
      9.7




 





  RMS
  9.4 (0.75 %)




RSD
15.2 (1.23 %)



 







Xxx
1022.9




Xyy
  850.7




Xzz -
 1873.6



  ETA -
 0.0919




Øz,a
0.19



  Øa,CI
0.01




Øz,CI
0.18



 







 








 







 
   



Table 3.  2-Iodopyridine and, for comparison, 2-Bromopyridine and Pyridine.  Molecular structure parameters, ropt (Å and degrees).

 






  2-I-
  2-Br-
 Pyridine








N(1)C(2) 1.3156
 1.3152 1.3336


C(2)C(3) 1.3932
 1.3909 1.3904


C(3)C(4) 1.3875
 1.3855 1.3885


C(4)C(5) 1.3901
 1.3901 1.3885


C(5)C(6) 1.3880
 1.3873 1.3904


C(6)N(1) 1.3364
 1.3355 1.3336


C(2)I/Br/H 2.1283
 1.8859 1.0880


C(3)H(3) 1.0827
 1.0818 1.0845


C(4)H(4) 1.0852
 1.0848 1.0851


C(5)H(5) 1.0839
 1.0834 1.0845


C(6)H(6) 1.0869
 1.0869 1.0880


C(6)N(1)C(2) 117.40
 117.16 117.03


N(1)C(2)C(3) 124.70
 124.74 123.80


C(2)C(3)C(4) 117.21
 117.37 118.44


C(3)C(4)C(5) 119.20
 119.13 118.50


C(4)C(5)C(6) 118.24
 118.09 118.44


C(5)C(6)N(1) 123.25
 123.51 123.80


N(1)C(2)I/Br/H 116.55
 116.95 115.94


C(2)C(3)H(3) 121.02
 120.76 120.21


C(3)C(4)H(4) 119.97
 120.11 120.75


C(4)C(5)H(5) 121.37
 121.51 121.35


C(5)C(6)H(6) 120.96
 120.73 120.26



 








 














Table 4.  2-Iodopyridine.  Atomic coordinates, ropt.
 







  a (Å)
  b (Å)







N(1)
1.3915 - 1.1739

C(2)
0.8033
0.0029

C(3)
1.4733
1.2243

C(4)
2.8602
1.1872

C(5)
3.5057
 - 0.0440

C(6)
2.7278 - 1.1934

I(2) - 1.3250
0.0025

H(3)
0.9281
2.1598

H(4)
3.4273
2.1124

H(5)
4.5874 - 0.1139

H(6)
3.1862
 - 2.1789


 








 












Table 5.  2-Iodopyridine.  Rotational Constants (MHz). 
 




Calc. ropt  Expt. [1]





A  5923.9 5870.2(3)

B    762.5
   768.919(9)

C    675.5
   679.788(7)



 








 








[1] W.Caminati and P.Forti, Chem.Phys.Lett. 29,239(1974).

 








 








IodobenzenePyridine 4-Iodopyridine

2-Bromopyridine
 2-Chloropyridine

3-Bromopyridine 3-Chloropyridine

4-Bromopyridine 4-Chloropyridine





 








 








Table of Contents





Molecules/Nitrogen




Molecules/Iodine




 








 













2IPyridine.html






Last Modified 19 Aug 2011