C5F5N



 

 








Nitrogen


Nuclear Quadrupole Coupling Constants


in Pentafluoropyridine


 







 

 


 




Nitrogen nqcc's in pentafluoropyridine were first determined by Doraiswamy and Sharma [1], and redetermined with improved resolution by Heineking and Dreizler [2].
 
Calculation was made here of the nitrogen nqcc's on a structure given by B3P86/6-31G(3d,3p) optimization.  These are compared with the experimental nqcc's [2] in Table 1.  Structure parameters are given in Table 2, atomic coordinates in Table 3, and rotational constants in Table 4.
 
In Table 1,  RMS is the root mean square difference between calculated and experimental nqcc's (percentage of the average of the magnitudes 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. Nitrogen nqcc's in Pentafluoropyridine (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
 




Calc.
Expt. [2]
   






14N Xaa 2.017 1.97(1)
Xbb - 3.878 - 3.94(1)
Xcc 1.861 1.97(1)
ETA * - 0.040
 
RMS 0.08 (2.9 %)
RSD 0.030 (1.3 %)
 
 
* ETA = (Xaa - Xcc)/Xbb = (Xxx - Xyy)/Xzz.
 
 
 
Table 2.  Pentachloropyridine, Pentafluoropyridine, and Pyridine.  Molecular structure parameters, ropt (Å and degrees).
 
C5X5N C5Cl5N C5F5N C5H5N
N(1)C(2) 1.3158 1.3104 1.3336
C(2)C(3) 1.3994 1.3878 1.3904
C(3)C(4) 1.4005 1.3898 1.3885
C(2)X(2) 1.7200 1.3226 1.0880
C(3)X(3) 1.7073 1.3244 1.0845
C(4)X(4) 1.7052 1.3178 1.0851
C(6)N(1)C(2) 119.64 118.46 117.03
N(1)C(2)C(3) 123.15 123.80 123.80
C(2)C(3)C(4) 117.25 117.31 118.44
C(3)C(4)C(5) 119.55 119.31 118.50
N(1)C(2)X(2) 116.53 117.59 115.94
C(4)C(3)X(3) 121.10 120.60 121.35


 
 
Table 3.  Pentafluoropyridine.  Atomic coordinates, ropt.
 
 a (Å)  b (Å)
N(1) 0.0 - 1.6430
C(2,6) ± 1.1260 - 0.9726
C(3,5) ± 1.1994 0.4132
C(4) 0.0 1.1153
F(2,6) ± 2.2520 - 1.6663
F(3,5) ± 2.3572 1.0563
F(4) 0.0 2.4332
 
 

Table 4.  Pentafluoropyridine.  Rotational Constants (MHz).
 
Calc ropt     Expt. [2]
A 1486.8 1481.5813(3)
B 1078.0 1075.3725(2)
C   624.9   623.1115(4)


 
 
[1] S.Doraiswamy and S.D.Sharma, Chem.Phys. 6,76(1974).
[2] N.Heineking and H.Dreizler, Z.Naturforsch. 42a,207(1987).
 
 

Pyridine Pentachloropyridine
2,6-Difluoropyridine

2-Fluoropyridine 2,3-Difluoropyridine 3,4-Difluoropyridine
3-Fluoropyridine 2,4-Difluoropyridine 3,5-Difluoropyridine
4-Fluoropyridine 2,5-Difluoropyridine
 
 

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Last Modified 15 Nov 2003