CF3-CF2I





 






Iodine


Nuclear Quadrupole Coupling Constants

in Perfluoroethyl Iodide

 







 
Calculation of the 127I nqcc tensor in perfluoroethyl iodide was made here on molecular structures given by MP2/6-311+G(d), MP2/6-311+G(2d), and MP2/6-311G(3d) optimizations; and on these same structures but with empirically corrected C-C and CF bond lengths.  These nqcc's are compared with experimental values in Tables 1 - 3.  Structure parameters are given in Table 4, rotational constants in Table 5.  Quartic centrifugal distortion constants, calculated and experimental, are given in Table 6.
 
In Tables 1 - 3, 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 (percent of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation of the B1LYP/6-311G(df,p) model for calculation of the nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's.
 

 







   






Table 1. 127I nqcc's in Perfluoroethyl Iodide (MHz).  
 
Calc (1) was made on the MP2/6-311+G(d) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected C-C and CF bond lengths.
 


Calc (1)
Calc (2)
  Expt [1]
   




Xaa - 1734.3 - 1729.2 - 1739.8608(95)
Xbb   666.3   668.6   663.0608(145)
Xcc 1068.0 1060.6 1076.8007(110)
|Xab| 1039.2 1023.6 1052.618(21)
 
RMS   6.3 (0.54 %) 11.6 (1.00 %)
RSD 15.2 (1.23 %) 15.2 (1.23 %)
 
Xxx 1053.7 1046.1 1058.945(48)
Xyy 1068.0 1060.6 1076.801(1)
Xzz - 2121.7 - 2106.7 - 2135.746(41)
ETA 0.0067 0.0069 0.00836(3)
Øz,a 20.44 20.24 20.611(1)
Øa,CI 22.01 21.87
Øz,CI   1.56   1.62
   
 
 

   






Table 2. 127I nqcc's in Perfluoroethyl Iodide (MHz).  
 
Calc (1) was made on the MP2/6-311+G(2d) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected C-C and CF bond lengths.
 


Calc (1)
Calc (2)
  Expt [1]
   




Xaa - 1719.0 - 1706.4 - 1739.8608(95)
Xbb   658.8   655.2   663.0608(145)
Xcc 1060.1 1051.2 1076.8007(110)
|Xab| 1033.3 1020.7 1052.618(21)
 
RMS 15.6 (1.35 %) 24.7 (2.13 %)
RSD 15.2 (1.23 %) 15.2 (1.23 %)
 
Xxx 1045.1 1035.2 1058.945(48)
Xyy 1060.1 1051.2 1076.801(1)
Xzz - 2105.2 - 2086.4 - 2135.746(41)
ETA 0.0071 0.0077 0.00836(3)
Øz,a 20.50 20.42 20.611(1)
Øa,CI 22.04 22.05
Øz,CI   1.54   1.63
   

   
 
   






Table 3. 127I nqcc's in Perfluoroethyl Iodide (MHz).  
 
Calc (1) was made on the MP2/6-311+G(3d) optimized molecular structure.
Calc (2) was made on this same structure but with empirically corrected C-C and CF bond lengths.
 


Calc (1)
Calc (2)
  Expt. [1]
   




Xaa - 1727.3 - 1717.6 - 1739.8608(95)
Xbb   662.4   661.4   663.0608(145)
Xcc 1064.9 1056.2 1076.8007(110)
|Xab| 1038.1 1023.2 1052.618(21)
 
RMS 10.0 (0.86 %) 17.6 (1.51 %)
RSD 15.2 (1.23 %) 15.2 (1.23 %)
 
Xxx 1050.4 1040.9 1058.945(48)
Xyy 1064.9 1056.2 1076.801(1)
Xzz - 2115.3 - 2097.1 - 2135.746(41)
ETA 0.0069 0.0073 0.00836(3)
Øz,a 20.49 20.35 20.611(1)
Øa,CI 22.06 22.00
Øz,CI   1.57   1.65
   
 
 
Table 4.  Perfluoroethyl Iodide.  Heavy atom structure parameters (Å and degrees).  Complete structures are given here in Z-matrix representation.
 
r (1) = MP2/6-311+G(d) opt
r (2) = r (1) with corrected C-C and CF bond lengths.
 
Point Group C1   r (1)   r (2)

CI 2.1587 2.1587
CC 1.5461 1.5371
CCI 112.46 112.46
 
r (1) = MP2/6-311+G(2d) opt
r (2) = r (1) with corrected C-C and CF bond lengths.
  r (1)   r (2)
CI 2.1321 2.1321
CC 1.5377 1.5371
CCI 112.73 112.73
 
r (1) = MP2/6-311+G(3d) opt
r (2) = r (1) with corrected C-C and CF bond lengths.
  r (1)   r (2)
CI 2.1480 2.1480
CC 1.5420 1.5371
CCI 112.42 112.42

 







 

Table 5.  Perfluoroethyl Iodide.  Rotational constants (MHz).  
 
r (1) = MP2/6-311+G(d) opt
r (2) = r (1) with corrected C-C and CF bond lengths.
  r (1)   r (2)    Expt.

A 2173.2 2195.6 2178.39031(38)
B   773.5   777.4   782.01491(18)
C   715.5   719.4   722.30778(14)
   
r (1) = MP2/6-311+G(2d) opt
r (2) = r (1) with corrected C-C and CF bond lengths.
A 2184.6 2204.6 2178.39031(38)
B   783.7   786.0   782.01491(18)
C   725.9   727.8   722.30778(14)
   
r (1) = MP2/6-311+G(3d) opt
r (2) = r (1) with corrected C-C and CF bond lengths.
A 2175.2 2197.8 2178.39031(38)
B   778.8   782.2   782.01491(18)
C   720.8   723.9   722.30778(14)

 
 
 
Table 6.  Perfluoroethyl Iodide.  Quartic Centrifugal Distortion Constants (kHz).
 
B3LYP * Expt [1]
Delta_J 0.0469 0.05148(98)
Delta_KJ 0.0638 0.0566(36)
Delta_K 0.124
delta_J 0.00554 0.00591(64)
delta_K 0.00950
 
* Run B3LYP/cc-pVTZ, with SDB-cc-pVTZ on I, opt output=pickett ---> extract the principal axes structure ---> then B3LYP/cc-pVTZ, with SDB-cc-pVTZ on I, freq=vibrot output=pickett.  Doug Fox, Gaussian Inc., private communication.
 
 
[1] G.S.Grubbs II and S.A.Cooke, J.Mol.Struct. 963,87(2010).
 
 
t-CH3CH2CH2I g-CH3CH2CH2I CH3I CH3CH2I
g-CH2ICH2F CH3-O-CH2I CH3CHICH3 (CH3)2CHCH2I
t-CF3CF2CH2I t-CF3CF2CF2I gt-CH2FCH2CH2I

 








 








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Last Modified 7 Oct 2012