H3C-CHFCl




 









Chlorine


Nuclear Quadrupole Coupling Constants

in 1-Chloro-1-Fluoroethane


 








 








 








Calculation of the chlorine nqcc's in 1-chloro-1-fluoroethane 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 in Z-Matrix format in Table 3.  Atomic coordinates and rotational constants are given in Tables 4 and 5, 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.  ě (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 H3C-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 - 62.78 - 62.88 - 62.4014(109)

Xbb
34.39
34.22
34.2641(138)

Xcc
28.39
28.66
28.1373(138)

Xab *
  0.61
  0.57



Xac *
26.69
26.12
25.5(64) **

Xbc *
  2.01
  1.97



 







RMS
0.27 (0.66 %) 0.41 (0.99 %)


RSD
0.49 (1.1 %)
0.49 (1.1 %)



 







Xxx
32.82
32.74



Xyy
37.20
37.07



Xzz - 70.02 - 69.81



ETA
0.062
0.062



ěz,a
  15.17
  14.86



ěz,b
  90.03
  90.03



ěz,c
105.17
104.86



ěz,CCl
    0.67
    0.54



 








 








* The algebraic signs of the off-diagonal components depend on the orientation of the molecule with respect to a,b,c axes.  Here, the algebraic signs (all positive) correspond to the atomic a,b,c coordinates given in Table 4.

** Absolute value.




 








 








   








Table 2.  37Cl nqcc's in H3C-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.
   








Xaa - 49.53 - 49.60 - 49.210(60)

Xbb
27.10
26.97
26.982(60)

Xcc
22.42
22.64
22.227(60)

Xab *
  0.38
  0.33



Xac *
20.95
20.50



Xbc *
  1.61
  1.58



 







RMS
0.23 (0.70 %) 0.33 (1.0 %)


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 a,b,c axes.  Here, the algebraic signs (all positive) correspond to the atomic a,b,c coordinates given in Table 4.

 








 








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.

 









 






Table 3. H3C-CHFCl  Structure parameters (┼ and degrees).  Point Group, C1.

 







Cl







C 1 R1





C 2 R2 1 A1



F 2 R3 1 A2 3 D1

H 2 R4 1 A3 3 D2

H 3 R5 2 A4 1 D3

H 3 R6 2 A5 1 D4

H 3 R7 2 A6 1 D5

 








MP2 Angles B3P86 Angles












R1 1.7757




R2 1.4992




R3 1.3685




R4 1.0888




R5 1.0879




R6 1.0893





R7 1.0878





A1 111.22 111.44



A2 108.48 108.13



A3 106.82 105.71



A4 110.10 110.13



A5 109.08 109.06



A6 109.69 110.17



D1 - 120.55 - 121.14



D2 124.05 123.85



D3   61.17   61.04



D4 - 178.83 - 179.31



D5 - 58.98 - 59.42





 








 
















Table 4.  H3C-CHF35Cl  Atomic coordinates, ropt,  MP2 Angles.
(More figures are shown than are significant.)
 









  a (┼)
  b (┼)
  c (┼)









Cl
1.254019 - 0.034883 - 0.046055

C - 0.465914 - 0.025623
0.395365

C - 1.171873 - 1.241484 - 0.125120

F - 1.032841
1.106192 - 0.124619

H - 0.491449
0.061864
1.480344

H - 0.733212 - 2.140729
0.302035

H - 2.222988 - 1.190327
0.156157

H - 1.092671 - 1.285933 - 1.209122


 








 













Table 5. H3C-CHF35Cl  Rotational constants (MHz).  MP2 and B3P86 angles.







MP2 ropt B3P86 ropt       Expt. [1]






A 9 112.3 9 066.4 9 016.268 55(37)

B 4 687.4 4 699.3 4 666.701 081(187)

C 3 352.8 3 350.8 3 329.369 097(152)


 








 








[1] R.Hinze, A.Lesarri, J.C.Lˇpez, J.L.Alonso, and A.Guarnieri, J.Chem.Phys. 104,9729(1996).

[2] I.Merke, L.Poteau, G.Wlodarczak, A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996).

[3] R.M.Villama˝an, W.D.Chen, G.Wlodarczak, J.Demaison, A.G.Lesarri, J.C.Lˇpez, and J.L.Alonso, J.Mol.Spectrosc. 171,223(1995)

[4] J.Demaison, J.CoslÚou, R.Bocquet, and A.G.Lesarri, J.Mol.Spectrosc. 167,400(1994).

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

 








 








CH3Cl CH3CH2Cl CH2ClCHF2 CH3CCl3

CF2ClCH3 CF2ClCHF2 CF2ClCH2F CF2ClCF3

CF3Cl CH2ClCF3 CH2ClCH2F


 








 








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Molecules/Chlorine




 








 













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Last Modified 17 Nov 2005