CH2=C(Cl)CCH




























 









Chlorine


Nuclear Quadrupole Coupling Constants


in 2-Chlorobuten-3-yne


 








 








 








Calculation of the chlorine nqcc's in 2-chlorobuten-3-yne was made on an approximate equilibrium structure derived here by MP2/aug-cc-pVTZ optimization with empirically corrected bond lengths.  These nqcc's are compared with the available experimental values [1] in Table 1.  Structure parameters are given in Table 2, rotational constants in Table 3.


 








In Table 1, 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 symmetry plane.  (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

RMS is the root mean square difference between calculated and experimental nqcc's (percent of average experimental value).  RSD is the calibration residual standard deviation for the B1LYP/TZV(3df,2p) model for calculation of the chlorine nqcc's, which may be taken as an estimate of the uncertainty in the calculated coupling constants.

 








 








   







Table 1. Chlorine nqcc's in 2-Chlorobuten-3-yne (MHz).
   










Calc.
Expt. [1]
   







35Cl Xaa - 27.35 - 27.1(1)



Xbb
- 6.00

- 6.4(1)



Xcc
33.36
33.5 *



|Xab|
56.51



 







RMS

0.3 (1.3 %)





RSD
0.49 (1.1 %)



 







Xxx
40.83




Xyy
33.36




Xzz - 74.19




ETA - 0.101




z,a
39.65




a,CCl
40.39




z,CCl
  0.74



   





37Cl Xaa - 23.11 -
21.8(3)



Xbb
- 3.18

- 4.0(3)



Xcc
26.29
25.8 *



|Xab|
44.22



 







RMS

0.9 (5.5 %)





RSD
0.44 (1.1 %)



 







 








* Calculated here from zero trace condition.


 









 

Table 2.  2-Chlorobuten-3-yne   Heavy atom structure parameters ( and degrees).  Complete structure is given here in Z-matix format.

 



Parameter
 reapprox




C(1)=C(2) 1.3345

C(2)Cl 1.7380

C(2)C(6) 1.4219

C(6)C(7) 1.2062

C(1)C(2)Cl 120.51

C(1)C(2)C(6)
124.66


 








 













Table 3.  2-Chlorobuten-3-yne  Rotational Constants (MHz), 35Cl species.   Calc is on the reapprox molecular structure.
 







 Calc.
  Expt. [1]







A
6896.2
6875.239(4)


B
3104.7
3096.353(2)


C
2140.9
2131.950(2)



 









 









[1] F.Karlsson, M.Granberg, and R.Vestin, Acta Chem. Scand. A 28,206(1974).


 








 








CH2=C=C=CHCl
t-1-Chlorobuten-3-yne 4-Chlorobuten-3-yne


 








 








Table of Contents




Molecules/Chlorine




 








 













2Clbuten3yne.html






Last Modified 29 Nov 2011