CF3(CF2)3CF2CN




 
 
 


Nitrogen


Nuclear Quadrupole Coupling Constants

in n-Perfluoropentyl gauche-anti


 







 
 
Calculation of the nitrogen nqcc's in n-perfluoropentyl cyanide, GA was made on structures given by B3P86/6-31G(2d) optimization (ropt), and on this same structure but with empirically derived equilibrium CF, C-C, and CN bond lengths (~ re).  These calculated nqcc's are given in Table 1.  Structure parameters are given in Table 2, rotational constants and electric dipole moments in Table 3.
 
In Table 1, subscripts a,b,c refer to principal axes of the inertia tensor; subscripts x,y,z to principal axes of the nqcc tensor.  Øz,CN (degrees) is the angle between the principal z-axis of the nqcc tensor and the CN bond axis.  ETA = (Xxx - Xyy)/Xzz.
RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's (unertainties in the structures not-with-standing).
 
 
 
   





Table 1.  14N nqcc's in n-perfluoropentyl cyanide, GA (MHz).  Calculation was made on ropt and ~ re structures
   





 ropt  ~ re Expt.
   




Xaa 1.847 1.843
Xbb - 3.471 - 3.478
Xcc 1.624 1.635
|Xab| 1.629 * 1.627 *
|Xac| 0.632 0.624
|Xbc| 2.169 2.148
 
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 2.304 2.298
Xyy 2.430 2.424
Xzz - 4.734 - 4.723
ETA 0.0266 0.0267
Øz,CN 0.31 0.30
 

 
* The algebraic sign of the product XabXacXbc is negative.
 
 
Table 2.  n-Perfluoropentyl Cyanide, GA.  Selected structure parameters, ropt and ~ re (Å and degrees).   Complete structures are given here in Z-matrix format.
 

  ropt   ~ re
C(1)C(2) 1.5469 1.5456
C(2)C(3) 1.5493 1.5479
C(3)C(4) 1.5495 1.5581
C(4)C(5) 1.5549 1.5533
C(5)C(6) 1.4758 1.4776
C(6)N(7) 1.1534 1.1544
C(1)C(2)C(3) 113.97 113.97
C(2)C(3)C(4) 113.13 113.13
C(3)C(4)C(5) 113.65 113.65
C(4)C(5)C(6) 113.15 113.15
C(5)C(6)N(7) 178.70 178.70
C(1)C(2)C(3)C(4) - 163.89 - 163.89
C(2)C(3)C(4)C(5) - 162.00 - 162.00
C(3)C(4)C(5)C(6)   73.93   73.93
C(4)C(5)C(6)N(7) 124.95 124.95

 
 
Table 3.  n-Perfluoropentyl Cyanide, GA.  Rotational Constants (MHz) and Dipole Moments (D).
 ropt  ~ re  Expt.
A 849.4 846.1
B 293.7 293.8
C 285.3 285.4
 
a| 0.65 0.65
b| 1.16 1.14
c| 0.49 0.49

 
 
For the all trans (Cs) conformer, the structure was optimized at the B3P86/6-31G(2d) level of theory.  A frequency calculation on this structure gives one imaginary frequency.  It is, therefore, a transition structure that connects two minima [1].
 
 
[1] J.B.Foresman and AE.Frisch, Exploring Chemistry with Electronic Structure Methods, 2nd ed., Gaussian, Inc. Pittsburgh, PA 1995-96.
 
 
n-Perfluoropentyl Cyanide transoid n-Perfluorobutyl Cyanide GA
n-Perfluorohexyl GA n-Perfluoroheptyl Cyanide GA
 

 








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Last Modified 27 May 2010