CH2I-CH2F




 




 
 
 

Iodine


Nuclear Quadrupole Coupling Constants


in gauche 1-Iodo-2-Fluoroethane


 







 
 
Calculation of the iodine nqcc's in gauche 1-iodo-2-fluoroethane was made on a molecular structure obtained by MP2/6-311G(3df,3pd) optimization, and on this structure but with empirically corrected C-C, CF, and CH bond lengths (approximate re).  These calculated nqcc's are compared with the experimental values of Niide and Ohkoshi [1] in Table 1.  Structure parameters are given in Table 2, rotational constants in Table 3.
 
In Table 1, subscripts a,b,c refer to the principal axes of the inertia tensor, subscripts 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 plane of the molecule.  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 residual standard deviation of calibration of the B1LYP/6-311G(df,p) model for calculation of the nqcc's.
 
 
   







Table 1.  127I nqcc's in g-CH2I-CH2F (MHz).
 
Calculation was made on the following structures:
ropt (1) = MP2/6-311G(3df,3pd) optimization, and
ropt (2)  = MP2/6-311G(3df,3pd) optimization with empirically corrected C-C, CF, and CH bond lengths.
   








Calc. (1)

Calc. (2)
Expt. [1]
   






Xaa - 1048.0 - 1048.2 - 1043.69(87)
Xbb   185.9   186.2   183.72(48)
Xcc   862.2   862.0   859.97(99)
|Xab| 1264.1 * 1264.5 * 1250.9(12) *
|Xac|   355.3   356.1   384.0(14)
|Xbc|   248.5   248.9   288.1(44)
 
RMS   3.1 (0.44 %)   3.2 (0.46 %)
RSD 15.2 (1.23 %) 15.2 (1.23 %)
 
Xxx   920.9   921.1   910.9
Xyy   984.6   985.0   995.1
Xzz - 1905.4 - 1906.1 - 1906.0
ETA 0.0334 0.0336 0.04417
Øz,CI 0.63 0.63
 
 
* The algebraic sign of the product XabXacXbc is negative.
 
 
Table 2.  g-CH2I-CH2F.  Heavy atom structure parameters (Å and degrees).  Complete structures are given here in Z-matrix format.
 
ropt(1) = MP2/6-311G(3df,3pd) optimization.
ropt(2) = MP2/6-311G(3df,3pd) optimization with MP2/6-311+G(d,p) corrected C-C and CF bond lengths, and MP2/6-31G(d,p) corrected CH bond lengths (see here).
ropt(1) ropt(2)
CI 2.1289 2.1289
C-C 1.5060 1.5043
CF 1.3765 1.3784
ICC 112.06 112.06
CCF 110.18 110.18
FCCI - 63.77 - 63.77
 
Table 3.  g-CH2I-CH2F.  Rotational Constants (MHz).
 
ropt(1) ropt(2) Expt. [1]
A 11 860.4 11 843.0 11 828.802(25)
B   1 779.1   1 780.1   1 740.2663(76)
C   1 620.8   1 621.4   1 588.7756(75)


  







 
[1] Y.Niide and I.Ohkoshi, J.Mol.Spectrosc. 140,301(1990).
 

 







CH3CH2I CH3I CH3-CHI-CH3
 

 








Table of Contents



Molecules/Iodine
 

 













gCH2ICH2F.html






Last Modified 10 Dec 2008