F3C-CHFCl




 









Chlorine


Nuclear Quadrupole Coupling Constants

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

 







 
 
Calculation of the chlorine nqcc's in 2-chloro-1,1,1,2-tetrafluoroethane was made on structures with bond lengths derived ab initio by the methods of the Lille group, as described below.  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.  Calculated nqcc's are compared with the experimental values [1] in Tables 1 and 2.  Structure parameters are given here in Z-Matrix format.  Atomic coordinates and rotational constants are given in Tables 3 and 4, respectively.
 
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.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
 
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 of the B1LYP/TZV(3df,2p) model for calculation of the chlorine nqcc's.
 
 
   






Table 1.  35Cl nqcc's in F3C-CHFCl (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. [1]
   





Xaa - 34.47 - 35.40 - 34.247(44)
Xbb   4.35   4.96   4.487(47)
Xcc 30.11 30.45 29.760(44)
Xab * - 47.47 - 47.19
Xac * 27.45 27.09
Xbc * 16.33 15.91
 
RMS 0.25 (1.1 %) 0.82 (3.6 %)
RSD 0.49 (1.1 %) 0.49 (1.1 %)
 
Xxx 35.56 35.51
Xyy 40.38 40.30
Xzz - 75.94 - 75.81
ETA 0.063 0.063
Øz,a   37.10   36.60
Øz,b   57.99   58.34
Øz,c 106.74 106.45
Øz,CCl     1.13     1.35
 

 
* The algebraic signs of the off-diagonal components depend on the orientation of the molecule with respect to the positive/negative sense of the a,b,c axes.  Here, the algebraic signs correspond to the atomic a,b,c coordinates given in Table 3.
 
 
   






Table 2.  37Cl nqcc's in F3C-CHFCl (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. [1]
   





Xaa - 28.19 - 28.92 - 26.95(51)
Xbb   4.45   4.91   4.53(27)
Xcc 23.74 24.01 22.42(49)
Xab * - 36.98 - 36.75
Xac * 21.80 21.50
Xbc * 12.57 12.24
 
RMS 1.05 (5.8 %) 1.48 (8.2 %)
RSD 0.44 (1.1 %) 0.44 (1.1 %)
 
 
* The algebraic signs of the off-diagonal components depend on the orientation of the molecule with respect to the positive/negative sense of the a,b,c axes.  Here, the algebraic signs correspond to the atomic a,b,c coordinates given in Table 3.
 
 
Molecular Structure
 
The molecular structure was optimized at the MP2/6-311+G(d,p) level of theory.  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. [4].  Likewise, the optimized CF bond lengths were corrected by regression analysis of the data given in Table VI of Ref. [3].  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. [2].  The CH bond lengths were corrected using r = 1.001 ropt, where ropt is obtained by MP2/6-31G(d,p) optimization [5].  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.
 
Structure parameters are given here in Z-Matrix format.
 
 
Table 3.  F3C-CHF35Cl  Atomic coordinates, ropt,  MP2 Angles.
 
 a (Å)  b (Å)  c (Å)
Cl - 1.8373 - 0.4845 0.0072
C - 0.4628 0.4704 - 0.4937
C 0.8334 - 0.1626 - 0.0100
F - 0.5371 1.7193 0.0233
H - 0.4468 0.5317 - 1.5804
F 0.8704 - 0.2655 1.3090
F 0.9784 - 1.3739 - 0.5401
F 1.8597 0.5893 - 0.4035
 
 
Table 4. F3C-CHF35Cl  Rotational constants (MHz).  MP2 and B3P86 angles.
 
MP2 ropt B3P86 ropt       Expt. [1]
A  3197.2  3202.4 3180.18047(76)
B  1807.7  1796.6 1786.04483(68)
C  1467.6  1462.1 1452.74333(74)
 
 
[1] J.C.López, A.Aguado, S.Blanco, and J.L.Alonso, J.Mol.Spectrosc. 175,370(1996).
[2] I.Merke, L.Poteau, G.Wlodarczak, A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996).
[3] 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)
[4] J.Demaison, J.Cosléou, R.Bocquet, and A.G.Lesarri, J.Mol.Spectrosc. 167,400(1994).

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

 







 
CH3CHFCl CH3CH2Cl CH2ClCHF2 CH3CCl3
CF2ClCH3 CF2ClCHF2 CF2ClCH2F CF2ClCF3
CF3Cl CH2ClCF3 CH2ClCH2F CH3Cl
 

 








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Last Modified 12 Feb 2006