ClF2C-CHF2

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Chlorine


Nuclear Quadrupole Coupling Constants

in 1-Chloro-1,1,2,2-Tetrafluoroethane

 







 
 
Calculation of the chlorine nqcc's in 1-chloro-1,1,2,2-trifluoroethane were made on structures with bond lengths derived ab initio by the methods of the Lille group, as described below.  Interatomic angles used are those given by (1) MP2/6-311+G(d,p), and (2) B3P86/6-311+G(3d,3p) optimization.  Calculated nqcc's are shown in Tables 1 and 2.  Structure parameters are given in Z-Matrix format in Table 3.
 
Calculation was made also on MP2/aug-cc-pVTZ ropt and approximate re structures.
 
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.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular symmetry plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
 
 
 
   






Table 1.  35Cl nqcc's in ClF2C-CHF2 (MHz).  Calculation was made on the ab initio structure with interatomic angles given by (1) MP2/6-311+G(d,p), and (2) B3P86/6-311+G(3d,3p) optimization.
   







Calc. (1)
Calc. (2)
Expt.
   





Xaa 15.72 14.28
Xbb - 53.87 - 52.43
Xcc 38.16 38.16
|Xab| 44.89 45.84
 
Xxx 37.72 37.61
Xyy 38.16 38.16
Xzz - 75.88 - 75.77
ETA 0.006 0.007
Øz,a 63.89 63.02
Øa,CCl 65.13 64.49
Øz,CCl   1.24   1.47
 

 
 
   






Table 2.  37Cl nqcc's in ClF2C-CHF2 (MHz).  Calculation was made on the ab initio structure with interatomic angles given by (1) MP2/6-311+G(d,p), and (2) B3P86/6-311+G(3d,3p) optimization.
   







Calc. (1)
Calc. (2)
Expt.
   





Xaa   9.90   8.79
Xbb - 39.98 - 38.87
Xcc 30.07 30.07
|Xab| 37.17 37.79
 
 
 
Molecular Structure
 
The molecular structure was optimized at the MP2/6-311+G(d,p) level of theory assuming Cs symmetry.  The optimized CC single bond length was then corrected using the equation obtained from linear regression analysis of the data given in Table IX of Ref.[3].  Likewise, the optimized CF bond lengths were corrected by regression analysis of the data given in Table VI of Ref.[2].  For the CCl bond, the structure was optimized at the MP2/6-311+G(2d,p) level and corrected by linear regression analysis of the data given in Table 4 of Ref.[1].  The CH bond lengths were corrected using r = 1.001 ropt, where ropt is obtained by MP2/6-31G(d,p) optimization [4].  Interatomic angles used in the calculation are those given by (1) MP2/6-311+G(d,p) and (2) B3P86/6-311+G(3d,3p) optimization.
 
 
Table 3. Structure parameters (Å and degrees).
 
Cl
C 1 R1
C 2 R2 1 A1
F 3 R3 2 A3 1   D3
F 3 R3 2 A3 1 - D3
H 3 R4 2 A4 1 180.
F 2 R5 3 A5 6   D5
F 2 R5 3 A5 6 - D5
 
MP2 Angles B3P86 Angles
R1 1.7394
R2 1.525
R3 1.3415
R4 1.091
R5 1.3394
A1 112.48 112.87
A3 109.44 109.70
A4 109.80 109.40
A5 108.03 108.19
D3   59.69   59.85
D5   58.14   58.27

 
 
[1] I.Merke, L.Poteau, G.Wlodarczak, A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996).
[2] R.M.Villamañan, W.D.Chen, G.Wlodarczak, J.Demaison, A.G.Lesarri, J.C.López, and J.L.Alonso, J.Mol.Spectrosc. 171,223(1995)
[3] J.Demaison, J.Cosléou, R.Bocquet, and A.G.Lesarri, J.Mol.Spectrosc. 167,400(1994).

[4] J.Demaison and G.Wlodarczak, Structural Chem. 5,57(1994).

 







 
CH3Cl CH3CH2Cl CH2ClCHF2 CH3CCl3
CF2ClCH3 CH2ClCH2F CF2ClCH2F CF2ClCF3
CF3Cl CH2ClCF3
 

 








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Last Modified 14 August 2003