C4N2F4




 







 


Nitrogen


Nuclear Quadrupole Coupling Constants


in Tetrafluoropyrimidine


 








 

 




Nitrogen nqcc's in tetrafluoropyrimidine were calculated on a structure given by B3P86/6-31G(3d,3p) optimization.  The results are shown in Table 1.  Structure parameters are given in Table 2,  atomic coordinates in Table 3, rotational constants in Table 4,
 
   







   








 







Table 1.  Nitrogen nqcc's in Tetrafluoropyrimidine (MHz).
 










Calc.
Expt. 
 







14N(1,3) Xaa 0.483


Xbb -
 2.234



Xcc 1.752


Xab ± 8.503


 








RSD 0.030 (1.3 %)
 








Xxx 2.129


Xyy 1.752


Xzz -
 3.880



ETA -
 0.097



Øz,a
58.44



Øa,bi
58.19



Øz,bi*
  0.26

   







 








* The z-axis makes an angle of 0.26o with the external bisector ( 'bi' ) of the C(2)N(1)C(6) angle, and tilts toward C(6).

 







 
Table 2.  Tetrafluoropyrimidine, Tetrachloroprimidine, and Pyrimidine.  Structure parameters ropt (Å and degrees).
 
X = F X = Cl X = H
C(2)N(3) 1.3174 1.3223 1.3320
N(3)C(4) 1.3135 1.3200 1.3328
C(4)C(5) 1.3885 1.4007 1.3877
C(2)X(2) 1.3152 1.7188 1.0876
C(4)X(4) 1.3151 1.7138 1.0879
C(5)X(5) 1.3231 1.7030 1.0835
N(1)C(2)N(3) 128.85 127.46 127.38
C(2)N(3)C(4) 114.78 116.02 115.70
N(3)C(4)C(5) 123.38 122.87 122.40
C(4)C(5)C(6) 114.84 114.77 116.44
C(5)C(4)X(4) 118.97 120.34 121.16
 
 
 
Table 3. Atomic coordinates, ropt
(More figures are shown than are significant.)
 
  a (Å)   b (Å)
N(1,3) 0.997606 ± 1.188303
C(2) 1.566307 0.0
C(4,6) - 0.315728 ± 1.170015
C(5) - 1.063384 0.0
F(2) 2.881513 0.0
F(4,6) - 0.942209 ± 2.326296
F(5) - 1.063384 0.0
 
 
Table 4.  Rotational Constants (MHz).
 
Calc. ropt Expt. 
A 1817.7
B 1355.1
C   776.3
 

 







Pyrimidine 2-Bromopyrimidine
2-Fluoropyrimidine 2-Cyanopyrimidine
4-Chloropyrimidine 5-Chloropyrimidine
2-Chloropyrimidine Tetrachloropyrimidine

 








 








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Last Modified 23 Feb 2004