cyclic-C5H5-CN
























 








Nitrogen


Nuclear Quadrupole Coupling Constants


in Cyclopentadiene-1-carbonitrile


 








 









The microwave spectrum of cyclopentadiene-1-carbonitrile was observed by Ford and Seitzman [1], by Sakaizuma et al. [2,3].  1,3- and 1,4- conformers, as shown below, have been identified:












1,3-Cyclopentadiene-1-carbonitrile 1,4-Cyclopentadiene-1-carbonitrile














At the MP2/6-311+G(d,p) opt level of theory, E1,3 < E1,4 by 6.1 kJ/mol.













Calculation of the nitrogen nqcc tensor in each conformer was made here on molecular structures given by B3P86/6-31G(3d,3p) and MP2/6-311+G(d,p) optimization, the latter with correction for the CN bond length.  These calculated nqcc's are given in Tables 1 and 2, rotational constants and dipole moments in Table 3.  Structure parameters are given here in Z-matrix format.


 








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In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor, subscripts 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 residual standard deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the efg's/nqcc's.

 








 








 








Table 1.  14N nqcc tensor in 1,3-Cyclopentadiene-1-carbonitrile (MHz).  Calculation was made here on the B3P86 and MP2 molecular structures (as discussed above).

 










Calc /B3P86

Calc /MP2

Expt

 








Xaa -
4.156
-
4.171




Xbb
2.352

2.357




Xcc
1.804

1.814




|Xab|
0.189

0.192













RSD
0.030 (1.3 %)
0.030 (1.3 %)












Xxx
2.358

2.363




Xyy
1.804

1.814




Xzz -
4.162
-
4.177




ETA -
0.133
-
0.131




Øz,a
1.66

1.68




Øa,CN
2.17

2.13




Øz,CN

0.50

0.45













   


















 








Table 2.  14N nqcc tensor in 1,4-Cyclopentadiene-1-carbonitrile (MHz).  Calculation was made here on the B3P86 and MP2 molecular structures (as discussed above).

 










Calc /B3P86

Calc /MP2

Expt

 








Xaa -
4.245
-
4.247




Xbb
2.256

2.257




Xcc
1.989

1.990




|Xab|
0.142

0.146













RSD
0.030 (1.3 %)
0.030 (1.3 %)












Xxx
2.259

2.260




Xyy
1.989

1.990




Xzz -
4.248
-
4.251




ETA -
0.0638
-
0.0635




Øz,a
1.25

1.29




Øa,CN
1.63

1.68




Øz,CN

0.38

0.39
























 










 



Table 3.  Cyclopentadiene-1-carbonitrile.  Rotational Constants (MHz) and Dipole Moments (D).








Calc /B3P86
Calc /MP2
 Expt [2]







1,3- A  8426
 8336
8353.7(9)


B  1914
 1899
1904.24(1)


C  1575
 1561
1565.38(1)


a|
 4.70
 4.69
4.15(15)


b|  0.35
 0.33
0.27(3)







1,4- A
 8382
 8222
8235.0(13)


B
 1913
 1897
1902.07(2)


C
 1569
 1556
1559.67(2)


a|  5.03
 5.02
4.36(25)


b|  0.58
 0.56
0.77(10)


 








 








[1] R.G.Ford and H.A.Seitzman, J.Mol.Spectrosc. 69,326(1978).


[2] T.Sakaizuma, H.Kikuchi, O.Ohashi, and I.Yamaguchi, Bull.Chem.Soc.Jpn. 60,3903(1987).


[3] T.Sakaizuma and H.Ishii, J.Mol.Spectrosc. 162,458(1993).











 









Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 15 Feb 2014