CF3-CF2Br



 





 





 





 





 









Bromine


Nuclear Quadrupole Coupling Constants

in Perfluoroethyl Bromide


 








 








 








Calculation of the bromine nqcc tensors in perfluoroethyl bromide was made on a molecular structure given by MP2/aug-cc-pVTZ optimization (ropt), and on same structure but with approximate equilibrium (~re) CCl, C-C, and CF bond lengths.  


 








Calculated nqcc tensors are compared with experimental values [1] in Tables 1 and 2.  Structure parameters are given in Table 3.  Rotational constants and dipole moments (given by B1LYP/TZV(3df,3p) calculation) are given in Tables 4 and 5.  Quartic centrifugal distortion constants, calculated and experimental, are given in Table 6.

 








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 root mean square difference between calculated and experimental diagonal nqcc's.  RSD is the calibration residual standard deviation of the B1LYP/TZV(3df,3p) model for calculation of the bromine nqcc's.

 









 







 
   








Table 1.  79Br nqcc's in CF3-CF2Br (MHz).  
   










 ropt

 ~re
   Expt. [1]
   








Xaa
430.70
433.67
430.6937(53)

Xbb - 120.37 - 123.32 - 121.7548(85)

Xcc - 310.33 - 310.35 - 308.9389(66)

|Xab|
367.52
364.98
364.06(12)

 







RMS
1.13 (0.39 %)
2.10 (0.73 %)



RSD
1.58 (0.39 %)
1.58 (0.39 %)



 







Xxx - 304.18 - 303.92



Xyy - 310.33 - 310.35



Xzz
614.51
614.27
611.459(96)

ETA
0.0100
0.0105



Øz,a
26.57
26.33



Øa,CBr
28.10
27.90



Øz,CBr
  1.53
  1.57



 








 








 








   








Table 2.  81Br nqcc's in CF3-CF2Br (MHz).  
   










  ropt

  ~re
Expt. [1]
   








Xaa
361.72
364.16
361.655(16)

Xbb - 102.45 - 104.87 - 103.5627(25)

Xcc - 259.27 - 259.29 - 258.092(19)

|Xab|
305.64
303.51
302.17(43)

 







RMS
0.94 (0.39 %)
1.77 (0.74 %)



RSD
1.38 (0.40 %)
1.38 (0.40 %)



 







Xxx - 254.13 - 253.92



Xyy - 259.27 - 259.29



Xzz
513.40
513.20
510.377(341)

ETA
0.0100
0.0105



Øz,a
26.39
26.15



Øa,CBr
27.92
27.72



Øz,CBr
  1.53
  1.57



 








 








 













Table 3.  CF3-CF2Br.  Selected structure parameters (Å and degrees).  Complete structures are given here in Z-matrix format.
 



CS

  ropt   ~re






 
C(2)Br 1.9083 1.9166
C(2)F(4,5) 1.3373 1.3313
C(2)C(3) 1.5450 1.5419
C(3)C(2)Br 111.18 111.18
C(3)C(2)F(4,5) 108.37 108.37
FC(2)F 108.49 108.49
F(4,5)C(2)Br 110.18 110.18






 








 













Table 4.  CF3-CF279Br  Equilibrium Rotational Constants (MHz) and Dipole Moments (D).







  ropt    ~re     Expt. [1]






A 2218.41 2233.09 2221.64214(26)

B 1061.23 1061.18 1052.53460(14)

C   962.15   961.96   954.65244(15)

 



a|   0.67   0.61

b|   0.27   0.24


 








 













Table 5.  CF3-CF281Br  Equilibrium Rotational Constants (MHz) and Dipole Moments (D).
 





  ropt    ~re     Expt. [1]






A 2217.18 2231.87 2220.3990(11)

B 1050.84 1050.74 1042.20662(50)

C   953.37   953.15   945.92279(52)

 



a|   0.67   0.61

b|   0.27   0.24


 








 








 





Table 6.  CF3-CF279Br  Quartic Centrifugal Distortion Constants (kHz).










B3LYP *
Expt [1]








Delta_J
0.0734
0.0729(13)

Delta_KJ
0.0394
0.0300(23)

Delta_K
0.116
0.1297(76)

delta_J
0.0107
0.00884(43)

delta_K - 0.0114



 





* Run B3LYP/cc-pVTZ opt output=pickett ---> extract the principal axes structure ---> then B3LYP/cc-pVTZ freq=vibrot output=pickett.  Doug Fox, Gaussian Inc., private communication.


 








 








[1] B.E.Long, G.S.Grubbs II, J.Langridge, and S.A.Cooke, J.Mol.Struct. 1023,55(2012);  B.E.Long, J.Langridge, S.A.Cooke, and G.S.Grubbs II, 66th International Symposium on Molecular Spectroscopy, Ohio State University, 2011, Abstract RH03.

 








 








CF3-CF2Cl CF3-CF2I CF3-CF2CN CH3CH2Br


 








 








Table of Contents




Molecules/Bromine




 








 













CF3CF2Br.html






Last Modified 7 Oct 2012