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.  Ø (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




Øz,a
17.86




Øa,CN
18.31




Øz,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




Øz,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.

 








 








Table of Contents




Molecules/Nitrogen




 








 













4Pentynenitrile.html






Last Modified 22 Aug 2017