N3C3H3




 







 


Nitrogen


Nuclear Quadrupole Coupling Constants


in 1,2,4-Triazine


 








 


 




Nitrogen nqcc's in 1,2,4-triazine were calculated on a structure given by B3P86/6-31G(3d,3p) optimization.  These are compared with the experimental nqcc's of Palmer and Christen [1] in Tables 1 - 3.  Structure parameters are given in Table 4, atomic coordinates in Table 5.
 
  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 andexperimental nqcc's (percent of the average magnitude of the experimental nqcc's).  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nqcc's.
 
   









 







Table 1.  N(1) nqcc's in 1,2,4-Triazine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
 










Calc.
Expt. [1]
 







14N(1) Xaa - 5.894 - 5.39(23)


Xbb 1.963
1.96(33)


Xcc 3.931 3.43(33)


|Xab| 0.715


 






RMS 0.41 (11.4 %)


RSD 0.030 (1.3 %)
 








Xxx 2.027


Xyy 3.931


Xzz -
5.958



ETA
0.320



Øz,a
  5.16



Øa,bi
14.60



Øz,bi*
  9.44

   







 








* The z-axis makes an angle of 9.44o with the external bisector ( 'bi' ) of the C(6)N(1)N(2) angle, and tilts toward the adjacent nitrogen, N(2).

 








 








 







Table 2.  N(2) nqcc's in 1,2,4-Triazine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
 










Calc.
Expt. [1]
 







14N(2) Xaa - 2.627 - 2.28(15)


Xbb - 0.595 -
0.66(24)


Xcc 3.222 2.93(24)


|Xab| 3.782


 






RMS 0.26 (13.5 %)


RSD 0.030 (1.3 %)
 








Xxx 2.305


Xyy 3.222


Xzz -
5.527



ETA
0.166



Øz,a
37.48



Øa,bi
47.22



Øz,bi*
  9.74

   






 
* The z-axis makes an angle of 9.74o with the external bisector ( 'bi' ) of the N(1)N(2)C(3) angle, and tilts toward the adjacent nitrogen, N(1).
 
 
 







Table 3.  N(4) nqcc's in 1,2,4-Triazine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
 










Calc.
Expt. [1]
 







14N(4) Xaa - 4.466 - 5.02(17)


Xbb 0.596
0.80(25)


Xcc 3.870 4.21(25)


|Xab| 1.663


 






RMS 0.39 (11.8 %)


RSD 0.030 (1.3 %)
 








Xxx 1.094


Xyy 3.870


Xzz -
4.964



ETA
0.559



Øz,a
16.65



Øa,bi
16.11



Øz,bi*
  0.54

   





 
* The z-axis makes an angle of 0.54o with the external bisector ( 'bi' ) of the C(3)N(4)C(5) angle, and tilts toward C(3).
 
 
Table 4.  1,2,4-Triazine.  Structure parameters ropt (Å and degrees).
 
N(1)N(2) 1.3250
N(2)C(3) 1.3317
C(3)N(4) 1.3348
N(4)C(5) 1.3241
C(5)C(6) 1.3928
C(6)N(1) 1.3291
C(3)H(3) 1.0864
C(5)H(5) 1.0878
C(6)H(6) 1.0854
N(1)N(2)C(3) 118.07
N(2)C(3)N(4) 127.19
C(3)N(4)C(5) 114.22
N(4)C(5)C(6) 120.63
C(5)C(6)N(1) 121.60
C(6)N(1)N(2) 118.28
N(2)C(3)H(3) 115.43
C(4)C(5)H(5) 117.64
C(5)C(6)H(6) 122.32
 
 
Table 5.  1,2,4-Triazine.  Atomic coordinates, ropt.
 
 a (Å)  b (Å)
N(1) - 1.2361 - 0.3284
N(2) - 0.9551 0.9435
C(3) - 0.3788 - 1.2607
N(4) 0.3483 1.2162
C(5) 0.9735 - 0.9272
C(6) 1.3557 0.3405
H(3) - 0.7227 - 2.2902
H(5) 0.6041 2.2720
H(6) 1.7503 - 1.6886
 
 
[1] M.H.Palmer and D.Christen, J.Mol.Struct. 612,401(2002).
 

 







1,2,3-Triazine 1,3,5-Triazine Pyridazine

 








 








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Molecules/Nitrogen




 








 













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Last Modified 8 Jan 2004