(CH2)4-C(H)CN





 


















 










Nitrogen


Nuclear Quadrupole Coupling Constants

in Cyanocyclopentane


 








 








The microwave spectrum of both axial and equatorial cyanocyclopentane was observed and assigned by Choe and Harmony [1]. 

 









For each conformer, calculation of the nitrogen nqcc tensor was made on a molecular structure given by B3P86/6-31G(3d,3p) optimization.  These calculated nqcc's are given in Tables 1 and 2.  Structure parameters are given here in Z-Matrix format, rotational constants and dipole moments in Table 3.


 








equatorial


axial



At the



B3P86/6-31G(3d,3p)

level of theory,


Eeq < Eax


by 1.4 kJ/mol
















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.  ETA = (Xxx - Xyy)/Xzz.  Ø (degrees) is the angle between its subscripted parameters.


RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen efg's/nqcc's.

 









 








 
 
 






Table 1.  Nitrogen nqcc tensor in equatorial cyanocyclopentane (MHz).  Calculation was made on a molecular structure given by B3P86/6-31G(3d,3p) optimization.

 
 









Calc.

Expt.

 
 






14N Xaa -
3.833





Xbb
2.082





Xcc
1.750





Xac

1.469





 






RSD
0.030 (1.3 %)




 






Xxx
2.113





Xyy
2.082




Xzz -
4.196





ETA -
0.0073





Øz,a
13.87





Øa,CN
13.92





Øz,CN
  0.05













 








 








 
 






Table 2.  Nitrogen nqcc tensor in axial cyanocyclopentane (MHz).  Calculation was made on a molecular structure given by B3P86/6-31G(3d,3p) optimization.

 
 









Calc.

Expt.

 
 






14N Xaa -
1.985





Xbb
2.042





Xcc -
0.056





Xac

3.018





 






RSD
0.030 (1.3 %)




 






Xxx
2.148





Xyy
2.042




Xzz -
4.190





ETA -
0.025





Øz,a
36.14





Øa,CN
36.46





Øz,CN
  0.32













 
























Table 3. Cyanocyclopentane, rotational constants (MHz) and dipole moments (D).








________equatorial_________ __________axial___________


Calc
 Expt [1]
Calc
 Expt [1]







A 6374
6324.905
4359
4297.196

B 1794
1790.937
2191
2210.245

C 1498
1497.792
2028
2057.205







a|
 4.47

 3.74


c|  0.72

 2.03



 








 








[1] J.-I.Choe and M.D.Harmony, J.Mol.Spectrosc 81,480(1980).


 








 








Cyanoyclopropane
Cyanocyclobutane




Cyanocyclohexane
Chlorocyclopentane




 









 








Table of Contents




Molecules/Nitrogen




 








 













CH24CHCN.html






Last Modified 24 Jan 2014