HCC-CH2CH2-CN

























 









Nitrogen


Nuclear Quadrupole Coupling Constants


in 4-Pentynenitrile



 
(4-Cyano-1-butyne)




 








 








Calculations of the nitrogen nqcc tensors in both trans and gauche conformers of 4-pentynenitrile were made on approximate equilibrium structures (~re) given by MP2/aug-cc-pVTZ optimization with empirically corrected CC and CN bond lengths.   These calculated nqcc's are compared with the experimental results of Hays, et al. [1] in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants in Table 4.

 


































trans


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.  (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 trans-4-Pentynenitrile (MHz).  Calculation was made on ~re molecular strcuture.
   










Calc

 Expt. [1]
   






14N Xaa -
3.656
-
3.6492(112)



Xbb - Xcc -
0.432
-
0.4200(236)



Xbb
1.612

1.6146(131) *



Xcc
2.044

2.0346(131) *



Xab
1.893













RMS

0.006 (0.3 %)





RSD

0.030 (1.3 %)












Xxx
2.222





Xyy
2.044




Xzz -
4.266





ETA
-
0.0418





z,a
17.86





a,CN
18.31





z,CN
  0.45













 








* Derived here from Xaa and Xbb - Xcc


 









 









   







Table 2.  Nitrogen nqcc's in gauche-4-Pentynenitrile (MHz).  Calculation was made on ~re molecular strcuture.
   










Calc

Expt. [1]
   






14N
Xaa
0.182

0.1134(106)



Xbb - Xcc -
3.706

3.6148(156)



Xbb -
1.944
-
1.8641(94) *



Xcc
1.762

1.7507(94) *



Xab -
2.810





Xac -
0.927





Xbc -
1.174













RMS

0.061 (4.9 %)





RSD

0.030 (1.3 %)












Xxx
2.220





Xyy
2.035




Xzz -
4.255





ETA
-
0.0436





z,CN
0.18













 








* Derived here from Xaa and Xbb - Xcc with the latter assumed negative, not positive as shown above.


 













Table 3.  4-Pentynenitrile: MP2/aug-cc-pVTZ optimized TT and GT structure parameters, with approximate equilibrium bond lengths (~re) given in parentheses.





 C
 C,1,B1
 C,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 C,1,B4,2,A3,3,D2,0
 N,5,B5,1,A4,2,D3,0
 H,4,B6,3,A5,2,D4,0
 H,1,B7,5,A6,6,D5,0
 H,1,B8,5,A7,6,D6,0
 H,2,B9,1,A8,5,D7,0
 H,2,B10,1,A9,5,D8,0






    trans
    gauche






 B1=1.53812016         (1.5353)
 B2=1.45725569         (1.4580)
 B3=1.21525969         (1.2044)
 B4=1.45899839         (1.4597)
 B5=1.17076193         (1.1560)
 B6=1.06219171
 B7=1.08963445
 B8=1.08963445
 B9=1.0905826
 B10=1.0905826
 A1=110.62053085
 A2=177.92636713
 A3=111.01596177
 A4=178.19924023
 A5=179.12523215
 A6=109.13403144
 A7=109.13403144
 A8=109.42564528
 A9=109.42564528
 D1=0.
 D2=180.
 D3=0.
 D4=180.
 D5=121.33807082
 D6=-121.33807082
 D7=58.58845819
 D8=-58.58845819
 B1=1.53752627       (1.5347)
 B2=1.45723221       (1.4580)
 B3=1.21504422       (1.2042)
 B4=1.45945281       (1.4601)
 B5=1.17079213       (1.1560)
 B6=1.06215228
 B7=1.09018147
 B8=1.08980139
 B9=1.09075798
 B10=1.09075352
 A1=111.72418045
 A2=177.95790239
 A3=111.66353974
 A4=179.01391445
 A5=179.29650435
 A6=108.61168624
 A7=108.6804212
 A8=108.40908879
 A9=109.44298713
 D1=0.67412767
 D2=-62.89309227
 D3=-44.71389402
 D4=131.94188011
 D5=76.59155168
 D6=-166.08564299
 D7=175.89901691
 D8=58.97585166








 













Table 4.  4-Pentynenitrile:  Rotational Constants (MHz).

 





   ~re    Expt. [1]






trans
A 25145.
25063.9565(86)


B   1489.
  1477.08556(105)


C   1430.
  1419.39735(97)






gauche
A
  6436.
  6548.4595(41)


B
  2497.
  2422.67511(122)


C
  1932.
  1894.27648(129)


 








 








[1] B.M.Hays, D.Mehta-Hurt, K.M.Jawad, A.O.Hernandez-Castillo, C.Abeysekera, D.Zhang, and  T.S.Zwier, Abstract WC01, 72nd ISMS, Champaign-Urbana, Illinois, 2017.


 








 








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Molecules/Nitrogen




 








 













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Last Modified 22 Aug 2017