2-Br-NC5H4










 





























Bromine and Nitrogen


Nuclear Quadrupole Coupling Constants


in 2-Bromopyridine


 








 








 


 





Nitrogen and bromine nqcc's in 2-bromopyridine were calculated on a structure given by B3P86/6-31G(3d,3p) optimization.  Calculated and experimental [1] nqcc's are compared in Tables 1 - 3.  Structure parameters are given in Table 4, atomic coordinates in Table 5, and rotational constants in Table 6.

 








In Tables 1 - 3, 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.  (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.  Bromine nqcc's in 2-79Bromopyridine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
   










Calc.
Expt. [1]
   







79Br Xaa
554.08
551.750(23)


Xbb - 308.38 - 304.172(15)


Xcc - 245.69 - 247.578(15)


Xab
  - 1.24




 





  RMS
2.54 (0.69 %)




RSD
1.58 (0.39 %)



 







Xxx - 308.39




Xyy - 245.69




Xzz
554.08



  ETA - 0.113




z,a
0.08



  a,CBr
0.24




z,CBr
0.16



 







 









 









   







Table 2. Nitrogen nqcc's in 2-79Bromopyridine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
   










Calc
Expt [1]

   







14N Xaa - 0.021 -
0.084(12)



Xbb - 3.036 -
3.005(8)



Xcc
3.057
3.089(8)



Xab
2.880
2.99(28)


 








RMS

0.045 (2.2 %)





RSD
0.030 (1.3 %)



 







Xxx
1.722




Xyy
3.057




Xzz - 4.779




ETA
0.279




z,a
58.82




a,bi
58.12




z,bi *
  0.69



 







 








* The z-axis makes an angle of 0.69o with the external bisector ( 'bi' ) of the C(6)N(1)C(2) angle, and tilts toward C(6).

 








 








   







Table 3.  Bromine and Nitrogen nqcc's in 2-81Bromopyridine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
   










Calc.
Expt. [1]
   







81Br Xaa
462.92
460.899(23)



Xbb - 257.65 - 254.098(15)



Xcc - 205.27 - 206.801(15)



Xab
  - 1.02




 





  RMS
2.53 (0.82 %)





RSD
1.38 (0.40 %)



 






14N Xaa
0.021
-
0.089(12)



Xbb - 3.036
- 3.001(8)



Xcc - 3.057

3.091(8)



Xab -
2.880

2.73(34)


 







RMS
0.049 (2.4 %)





RSD
0.030 (1.3 %)



 







 








 







 
   


Table 4.  2-Bromopyridine and Pyridine.  Molecular structure parameters, ropt ( and degrees).

 






Pyridine







N(1)C(2) 1.3152 1.3336


C(2)C(3) 1.3909 1.3904


C(3)C(4) 1.3855 1.3885


C(4)C(5) 1.3901 1.3885


C(5)C(6) 1.3873 1.3904


C(6)N(1) 1.3355 1.3336


C(2)Br 1.8859


C(3)H(3) 1.0818 1.0845


C(4)H(4) 1.0848 1.0851


C(5)H(5) 1.0834 1.0845


C(6)H(6) 1.0869 1.0880


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


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


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


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


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


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


N(1)C(2)Br 116.95


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


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


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


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



 








 














Table 5.  2-Bromopyridine.  Atomic coordinates, ropt.  Normal species.
 







  a ()
  b ()







N(1)
0.8680 - 1.1783

C(2)
0.2770 - 0.0034

C(3)
0.9418
1.2184

C(4)
2.3270
1.1896

C(5)
2.9785 - 0.0383

C(6)
2.2034 - 1.1889

Br(2) - 1.6089
0.0046

H(3)
0.3897
2.1487

H(4)
2.8905
2.1166

H(5)
4.0598 - 0.1055

H(6)
2.6679 - 2.1716


 








 












Table 6.  2-Bromopyridine.  Rotational Constants (MHz).   Normal species.
 




Calc. ropt     Expt. [1]





A  5935.0 5869.9332(16)

B  1034.6 1026.14509(25)

C    881.0   873.37531(20)



 









[1] A.Y.Chung, E.A.Arsenault, S.L.Stephens, W.C.Pringle, C.A.Jimnez-Hoyos, S.A.Cooke, and S.E.Novick, J.Mol.Spectrosc. 356,28(2019).

 









A.Y.Chung, E.A.Arsenault, and S.E.Novick, Abstract FB06, 72nd ISMS, Champaign-Urbana, Illinois, 2017.


W.Caminati and P.Forti, Chem.Phys.Lett. 15,343(1972): For 79Br, Xaa = 552.2(12) MHz and Xbb = -304.4(6) MHz; and for 81Br, Xaa = 460.4(20) MHz and Xbb = -252.6(7) MHz.

 








 








Pyrimidine Pyridine Pyrazine

3-Bromopyridine 2-Chloropyridine

4-Bromopyridine 3-Chloropyridine

2-Fluoropyridine 4-Fluoropyrimidine

 








 








Table of Contents





Molecules/Nitrogen




Molecules/Bromine




 








 













2MBrP.html






Last Modified 29 Dec 2018