CH2=CCl-CH=CH2




 






















 









Chlorine


Nuclear Quadrupole Coupling Constants


in 2-Chloro-1,3-butadiene


 








 








 








Calculation of the Cl nqcc tensors in 2-chloro-1,3-butadiene was made on the substitution structure of Cederbalk and  Karlsson [1], and on an approximate re structure given by MP2/aug-cc-pVTZ optimization with empirical correction of the C=C, C-C, anf CCl bond lengths.  Calculated and experimental nqcc's [2] are compared in Table 1, structure parameters are given in Table 2.

 








In Table 1, 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 B1LYP/TZV(3df,2p) model for calculation of the chlorine nqcc's. 

Subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

 








 







 
   








Table 1. Chlorine nqcc's in CH2=CCl-CH=CH2 (MHz).  Calculation was made on the rs and approximate re structures.

   











Calc / rs
Calc / re
Expt. [2]
   








35Cl Xaa
  4.87
  5.91
  5.2(2)


Xbb - 37.02
 -
 37.83
 - 37.5(2)


Xcc
32.14
31.92
32.3


|Xab|
51.03
50.40



 









RMS
0.35 (1.4 %)
0.50 (2.0 %)




RSD
0.49 (1.1 %)
0.49 (1.1 %)



 









Xxx
39.09
38.98




Xyy
32.14
31.92




Xzz - 71.23
 -
 70.90




ETA - 0.0974 -
 0.0996




Øz,a
56.16
56.73




Øa,CCl
57.33
57.66




Øz,CCl
  1.17
  0.93



   







37Cl Xaa
  0.56
  1.37




Xbb - 25.90 -
 26.53




Xcc
25.33
25.15




|Xab|
41.41
40.99



 









RSD
0.44 (1.1 %)
0.44 (1.1 %)



 









 








 








 













Table 2.  2-Chloro-1,3-butadiene.  Heavy atom structure parameters, rs [1] and approximate re (Å and degrees).  The complete structures are given here in Z-matrix format.
 





   rs    re



CCl
 1.741(9)
 1.7367
C(2)=C(3)
 1.349(5)
 1.3360
C(3)--C(4) 1.447(9)
 1.4560
C(4)=C(5) 1.341(4)
 1.3351
ClC(3)=C(2)
 118.4(7)
 119.31
C(2)=C(3)--C(4) 123.9(6)
 123.64
C(3)--C(4)=C(5) 125.8(3)
 125.83
 







 








 








[1] P.Cederbalk and F.Karlsson, Acta.Chem.Scand. A 35,7(1981).

[2] F.Karlsson and Z.Smith, Acta.Chem.Scand. A 33,483(1979).

 








 








CH2=CHCl c-1-Chloro-1,3-butadiene



 








 








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Molecules/Chlorine




 








 













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Last Modified 16 Dec 2011