2-Cl-6-F-C5H3N
























 





 








Nitrogen and Chlorine

Nuclear Quadrupole Coupling Constants

in 2-Chloro-6-Fluoropyridine

 








 








 








Calculation was made of the nitrogen and chlorine nqcc tensors in 2-chloro-6-fluoropyridine on a molecular structure giveen by B3P86/6-31G(3d,3p) optimization.  These are compared with the experimental values of Arnold et al. [1] in Tables 1 - 3.  Structure parameters are given in Table 4, atomic coordinates in Table 5, and rotational constants in Table 6, centrifugal distortion constants in Table 7.

 








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.  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.  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the N efg's/nqcc's, and the B1LYP/TZV(3df,2p) model for calculation of the Cl efg's/nqcc's.

 








 








   






Table 1. Nitrogen nqcc's in 2-35Cl-6-Fluoropyridine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.

 









Calc
Expt [1] *
   






14N Xaa
1.609
1.444(66)


Xbb - 3.961 -
 3.938(47)


Xcc
2.352
2.494(47)


|Xab|
1.406
1.45(85)


 






RMS
0.126 (4.8 %)




RSD
0.030 (1.3 %)



 






  Xxx
1.944




Xyy
2.352




Xzz - 4.296




ETA
0.095




Øz,a
76.60




Øa,bi
76.81




Øz,bi **
  0.21



 







 








* Calculated here from experimental 1.5Xaa = 2.166(99) and 0.25(Xbb - Xcc) = -1.608(17) MHz using Kisiel's program QDIAG.

** The z-axis makes an angle of 0.21o with the external bisector ( 'bi' ) of the C(6)N(1)C(2) angle, and tilts toward C(2).

 








 








   






Table 2.  Chlorine nqcc's in 2-35Cl-6-Fluoropyridine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
   









Calc
Expt [1] *
   






35Cl Xaa - 60.14 -
 59.93(8)


Xbb
29.83
28.85(6)


Xcc
30.31
31.09(6)


|Xab|
34.64
34.23(49)


 






RMS
0.73 (1.8 %)




RSD
0.49 (1.1 %)



   





  Xxx
41.62




Xyy
30.31




Xzz - 71.93




ETA - 0.157




Øz,a
18.80




Øa,CCl
18.64




Øz,CCl
  0.16



 







 








* Calculated here from experimental 1.5Xaa = -89.90(12) and 0.25(Xbb - Xcc) = -0.560(19) MHz.

 








 








   






Table 3.  Nitrogen and Chlorine nqcc's in 2-37Cl-6-Fluoropyridine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
   









Calc
Expt [1] *
   






14N Xaa
1.586
1.67(9)


Xbb - 3.938 -
 4.02(6)


Xcc
2.352
2.34(6)


|Xab|
1.451




 





  RMS
0.068 (2.6 %)




RSD
0.030 (1.3 %)



   





37Cl Xaa - 47.83
47.55(12)


Xbb
23.94
23.12(8)


Xcc
23.89
24.43(8)


|Xab|
26.73
26.8(20)


 





  RMS
0.59 (1.9 %)




RSD
0.44 (1.1 %)



 







 








* Calculated here from experimental 1.5Xaa = 2.51(13) and 0.25(Xbb - Xcc) = -1.590(21) MHz for N, and  1.5Xaa = -71.33(18) and 0.25(Xbb - Xcc) = -0.327(26) for Cl.

 







 
 


Table 4.  2-Chloro-6-Fluoropyridine.  Molecular structure parameters, ropt (Å and degrees).
 




N(1)C(2) 1.3217


C(2)C(3) 1.3895


C(3)C(4) 1.3894


C(4)C(5) 1.3872


C(5)C(6) 1.3873


C(6)N(1) 1.3116


C(2)Cl(2) 1.7334


C(3)H(3) 1.0815


C(4)H(4) 1.0846


C(5)H(5) 1.0820


C(6)F(6) 1.3316


C(6)N(1)C(2) 116.53


N(1)C(2)C(3) 124.47


C(2)C(3)C(4) 117.08


C(3)C(4)C(5) 119.87


C(4)C(5)C(6) 116.30


C(5)C(6)N(1) 125.75


N(1)C(2)Cl(2) 116.44


C(2)C(3)H(3) 120.67


C(3)C(4)H(4) 120.00


C(4)C(5)H(5) 123.05


C(5)C(6)F(6) 118.62



 








 














Table 5.  2-35Cl-6-Fluoropyridine.  Atomic coordinates, ropt.  Normal species.
 







 a (Å)
 b (Å)







N(1) -
 0.1808 - 0.8318

C(2)
0.7551
0.1016

C(3)
0.5030
1.4680

C(4) - 0.8284
1.8655

C(5) - 1.8346
0.9106

C(6) - 1.4243 - 0.4146

Cl(2)
2.3975 - 0.4523

H(3)
1.3176
2.1793

H(4) - 1.0791
2.9207

H(5) - 2.8869
1.1622

F(6) - 2.3523 - 1.3696


 








 












Table 6.  2-35Cl-6-Fluoropyridine.  Rotational Constants (MHz).   Normal species.
 




Calc ropt     Expt [1]





A  3439.0 3420.8161(15)

B  1260.7 1258.4740(17)

C    922.5   919.9140(13)



 








 








 




Table 7.  2-35Cl-6-Fluoropyridine.  Quartic Centrifugal Distortion Constants (kHz).  Calc = B3LYP/cc-pVTZ
 







Calc.
Expt [1]







DJ
0.0335
0.027(19)

DJK
0.0489


DK
0.605


d1
 -
 0.0116


d2 -
 0.00213









 








 








[1] S.Arnold, J.C.Chewning, and G.Brown, Abstract RE12, 69th International Symposium on Molecular Spectroscopy, Champaign-Urbana, Ill. 2014.

 








 








Pyridine 2-Chloropyridine 2,4-Dichloropyridine

2-Chloro-3-Fluoropyridine 2-Chloro-4-Fluoropyridine 2-Chloro-5-Fluoropyridine

 








 








Table of Contents





Molecules/Nitrogen




Molecules/Chlorine




 








 













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Last Modified 1 Aug 2014