C2H2N2S




 

 





 


Nitrogen


Nuclear Quadrupole Coupling Constants


in 1,2,4-Thiadiazole


 







 

 


 




Calculation of the nitrogen nqcc's in 1,2,4-Thiadiazole was made on the substitution molecular structure of Stiefvater [1,2].  These are given in Tables 1 and 2.  Structure paameters are given in Table 3.
 
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.
RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of nitrogen nqcc's.
 
 
   







Table 1.  N(2) nqcc's in 1,2,4-Thiadiazole (MHz).  Calculation was made on the rs structure of Stiefvater [1,2].
   










Calc.
Expt.
   






14N(2) Xaa 1.095
Xbb - 2.267
Xcc 1.172
|Xab| 2.944
 
RSD 0.030 (1.3 %)
 
Xxx 2.805
Xyy 1.172
  Xzz - 3.977
  ETA - 0.410
Øz,a 59.86
Øa,bi 74.79
Øz,bi * 14.93
 
 
* The z-axis makes an angle of 14.93o with the external bisector ('bi') of the SNC angle and tilts toward S(1).
 
 
   







Table 2.  N(4) nqcc's in 1,2,4-Thiadiazole (MHz).  Calculation was made on the rs structure of Stiefvater [1,2].
   










Calc.
Expt.
   






14N(4) Xaa - 2.881
Xbb 0.387
Xcc 2.494
|Xab| 2.373
 
RSD 0.030 (1.3 %)
 
Xxx 1.634
Xyy 2.494
  Xzz - 4.128
  ETA 0.208
Øz,a 27.72
Øa,bi 27.25
Øz,bi *   0.47
 
 
* The z-axis makes an angle of 0.47o with the external bisector ('bi') of the CNC angle and tilts toward C(5).
 
 
 
Table 3.  1,2,4-Thiadiazole.  Molecular structure parameters, rs [1,2] (Å and degrees).
 
S(1)N(2) 1.6492(10)
N(2)C(3) 1.3165(10)

C(3)N(4) 1.3665(15)
N(4)C(5) 1.3135(15)
C(5)S(1) 1.7073(15)
C(5)H(5) 1.0784(10)
C(3)H(3) 1.0780(20)
C(5)S(1)N(2)   92.76(10)
S(1)N(2)C(3) 107.09(5)
N(2)C(3)N(4) 120.13(10)
C(3)N(4)C(5) 107.73(5)
N(4)C(5)S(1) 112.30(5)
S(1)C(5)H(5) 123.90(5)
N(4)C(3)H(3) 119.94(20)


 
 

[1] O.L.Stiefvater, Z.Naturforsch. 31a,1681(1976).
[2] Landolt-Börnstein, Numerical Data and Functional Relationships in Science and Technology, New Series, ed. O.Madelung, Group II, Volume 15, Structure Data of Free Polyatomic Molecules, eds: K.-H.Hellwege and A.M.Hellwege, Springer-Verlag, Berlin.

 








 







Thiazole 1,3,4-Oxadiazole 1,2,5-Oxadiazole
1,2,3-Thiadiazole 1,2,5-Thiadiazole 1,3,4-Thiadiazole
 

 








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Molecules/Nitrogen



 

 













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Last Modified 24 May 2003