CH3CH2CH(CN)CH3















 









Nitrogen


Nuclear Quadrupole Coupling Constants


in gauche 2-Methylbutyronitrile



 
(2-Cyano-gauche-butane)




 








 
Click for 2-Methylbutyronitrile anti













Calculations of the nitrogen nqcc tensors in gauche 2-methylbutyronitrile was made on approximate equilibrium structures (~re) of the conformers shown below, given by MP2/6-311+G(3df,3pd) optimization with empirically corrected CC and CN bond lengths.   These calculated nqcc's are compared with the experimental results of Hermanns, et al. [1] in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants in Table 4.

 








                        gauche (+)


gauche (-)                              
























 









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.  Ĝ (degrees) is the angle between its subscripted parameters.


RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation for the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen  efg's/nqcc's.

 








 









   







Table 1.  Nitrogen nqcc's in gauche (+) 2-Methylbutyronitrile (MHz).  Calculation was made on ~re molecular strcuture.
   










Calc

Expt. [1]
   






14N Xaa -
1.930
-
1.902(13)



Xbb
0.355

0.296(17)



Xcc
1.575

1.606(15)



Xab
2.673





Xac
1.413





Xbc -
0.932













RMS

0.042 (3.3 %)





RSD

0.030 (1.3 %)












Xxx
2.072





Xyy
2.120




Xzz -
4.192





ETA

0.0114





Ĝz,CN
0.50













 









 








 
   







Table 2.  Nitrogen nqcc's in gauche (-) 2-Methylbutyronitrile (MHz).  Calculation was made on ~re molecular strcuture.
   










Calc

Expt. [1]
   






14N Xaa -
3.400
-
3.358(47)



Xbb
1.505

2.26(43)



Xcc
1.895

1.10(45)



Xab
1.778





Xac
1.103





Xbc -
0.362













RMS

0.63 (28 %)





RSD

0.030 (1.3 %)












Xxx
2.081





Xyy
2.117




Xzz -
4.198





ETA

0.00840





Ĝz,CN
0.37













 








 













Table 3.  gauche 2-Methylbutyronitrile: MP2/6-311+G(3df,3pd) optimized structure parameters, with approximate equilibrium bond lengths (~re) given in parentheses.





 C
 C,1,B1
 H,1,B2,2,A1
 H,1,B3,2,A2,3,D1,0
 H,1,B4,2,A3,4,D2,0
 C,2,B5,1,A4,5,D3,0
 H,2,B6,1,A5,6,D4,0
 C,6,B7,2,A6,1,D5,0
 H,6,B8,2,A7,1,D6,0
 H,6,B9,2,A8,1,D7,0
 H,8,B10,6,A9,2,D8,0
 H,8,B11,6,A10,2,D9,0
 H,8,B12,6,A11,2,D10,0
 C,2,B13,1,A12,6,D11,0
 N,14,B14,2,A13,1,D12,0
gauche (+)








 B1=1.53052395     (1.5280)
 B2=1.08786778
 B3=1.08738387
 B4=1.08929978
 B5=1.53698514      (1.5341)
 B6=1.09207359
 B7=1.52250368      (1.5203)
 B8=1.0907562
 B9=1.09172054
 B10=1.08831359
 B11=1.08831921
 B12=1.08982969
 B13=1.46411844      (1.4648)
 B14=1.17061473      (1.1577)
 A1=110.77323496
 A2=111.02227152
 A3=109.47342633
 A4=112.97825498
 A5=108.65294172
 A6=113.76622491
 A7=108.46173702
 A8=107.3604586
 A9=110.31694981
 A10=111.70733384
 A11=110.8612091
 A12=110.05424191
 A13=178.50768385
 D1=120.13350404
 D2=120.04055576
 D3=55.21412257
 D4=-120.0127453
 D5=61.94697462
 D6=-175.75165087
 D7=-60.32599287
 D8=176.39462368
 D9=-63.94703419
 D10=56.90208587
 D11=123.29514466
 D12=-74.10418043










 



 C
 C,1,B1
 H,1,B2,2,A1
 H,1,B3,2,A2,3,D1,0
 H,1,B4,2,A3,4,D2,0
 C,2,B5,1,A4,3,D3,0
 H,2,B6,1,A5,6,D4,0
 C,6,B7,2,A6,1,D5,0
 H,6,B8,2,A7,1,D6,0
 H,6,B9,2,A8,1,D7,0
 H,8,B10,6,A9,2,D8,0
 H,8,B11,6,A10,2,D9,0
 H,8,B12,6,A11,2,D10,0
 C,2,B13,1,A12,6,D11,0
 N,14,B14,2,A13,1,D12,0
gauche (-)









 B1=1.53042925     (1.5279)
 B2=1.08782812
 B3=1.0894168
 B4=1.08730194
 B5=1.53573944     (1.5329)
 B6=1.09326817
 B7=1.52258048     (1.5204)
 B8=1.0917591
 B9=1.0905375
 B10=1.08833321
 B11=1.09034826
 B12=1.08798071
 B13=1.46336273     (1.4640)
 B14=1.17049378     (1.1568)
 A1=110.83469299
 A2=110.11094429
 A3=110.32684852
 A4=112.95955108
 A5=109.11426502
 A6=112.6054018
 A7=108.46076869
 A8=108.50293579
 A9=110.41609612
 A10=110.88034345
 A11=111.85616071
 A12=109.65718101
 A13=178.55240634
 D1=119.93920365
 D2=120.05268519
 D3=-176.3822666
 D4=-120.77920262
 D5=-62.71092791
 D6=59.8052351
 D7=175.57433889
 D8=-174.65975878
 D9=-55.21280536
 D10=65.57475659
 D11=122.20172503
 D12=-72.69344568









 













Table 4.  gauche 2-Methylbutyronitrile:  Rotational Constants (MHz).

 





   ~re     Expt. [1]






gauche (+)
A   4471.
4408.3867(14)


B   2942.
2910.49627(62)


C   2203.
2167.12146(12)






gauche (-)
A
  6621. 6482.4021(35)


B
  2232. 2212.96309(14)


C
  1791. 1768.70485(12)


 








 








[1] M.Hermanns, N.Wehres, F.Lewen, H.S.P.Müller, S.Schlemmer, J.Mol.Spectros. 358,25(2019).


 









M.Hermanns, N.Wehres, F.Lewen, H.S.P.Müller, S.Schlemmer, Abstract WJ05, 73rd ISMS, Champaign-Urbana, Illinois, 2018.

 









 








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Molecules/Nitrogen




 








 













2MeBuCN_gauche.html






Last Modified 29 Dec 2018