CH3-CHCl-C(=O)OH



 






Chlorine


Nuclear Quadrupole Coupling Constants

in 2-Chloropropionic Acid

 







 
 
Complete 35Cl and 37Cl nqcc tensors in 2-chloropropionic acid were determined by Lesarri et al. [1].
Calculation of the nqcc tensors was made here on structures derived ab initio as discussed below.  These are compared with the experimental nqcc tensors in Tables 1 and 2.
 
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, which may be taken as an estimate of the uncertainty in the calculated nqcc's.
 
 
   






Table 1.  35Cl nqcc's in CH3-CHCl-C(=O)OH (MHz).  Calculation was made on the ab initio structures ropt(1) and ropt(2). 
   







Calc. (1)
Calc. (2)
Expt. [1]
   





Xaa - 18.11 - 18.22 - 17.70(1)
Xbb - Xcc - 10.09 - 9.58 - 9.69(1)
Xbb   4.01   4.32   4.005 *
Xcc 14.10 13.90 13.695 *
|Xab| ** 43.06 43.18 42(2)
|Xac| 35.81 35.79 36(4)
|Xbc| 29.46 29.34 29(2)
 
RMS 0.33 (2.8 %) 0.37 (3.1 %)
RSD 0.49 (1.1 %) 0.49 (1.1 %)
 
Xxx 36.51 36.56 36.8(9)
Xyy 38.98 38.96 38.2(6)
Xzz - 75.49 - 75.52 - 74.9(11)
ETA 0.033 0.032 0.018(15)
Øz,a 45.70 45.61 45.7(2)
Øz,b 56.73 56.82 57.0(3)
Øz,c 62.64 62.64 62.3(4)
Øz,CCl   1.72   1.70
 

 
* Calculated here from the experimental Xaa and Xbb - Xcc.
** The algebraic sign of the product XabXacXbc is negative.
 
 
   






Table 2.  37Cl nqcc's in CH3-CHCl-C(=O)OH (MHz).  Calculation was made on the ab initio structures ropt(1) and ropt(2). 
   







Calc. (1)
Calc. (2)
Expt. [1]
   





Xaa - 15.95 - 16.08 - 15.67(1)
Xbb - Xcc - 7.27 - 6.77 - 6.84(1)
Xbb   4.34   4.66   4.415 *
Xcc 11.61 11.42 11.255 *
|Xab| ** 33.80 33.86 32(5)
|Xac| 28.40 28.41 30(6)
|Xbc| 22.43 22.33 22(3)
 
RMS 0.27 (2.5 %) 0.29 (2.8 %)
RSD 0.44 (1.1 %) 0.44 (1.1 %)
 
Xxx 28.78 28.81 31(2)
Xyy 30.72 30.70 28(2)
Xzz - 59.50 - 59.52 - 59(3)
ETA 0.033 0.032 - 0.05(5)
Øz,a 44.61 44.50 44.6(4)
Øz,b 57.57 57.71 58.6(11)
Øz,c 63.03 63.01 62.0(11)
Øz,CCl   1.72   1.70
 
 
* Calculated here from the experimental Xaa and Xbb - Xcc.
** The algebraic sign of the product XabXacXbc is negative.  
 
 
Molecular Structure
 
ropt(1):  The molecular structure was optimized at the MP2/6-31G(d,p), MP2/6-311+G(d,p), and MP2/6-311+G(2d,p) levels of theory.  C-H, C-C, C=O, and C-Cl bond lengths were corrected as described here.  Interatomic and dihedral angles, and the C-O-H geometry are those given by MP2/6-311+G(d,p) optimization.
 
ropt(2):  The molecular structure was optimized at the MP2/6-31G(d,p), MP2/6-311+G(d,p), and MP2/6-311+G(2d,p) levels of theory.  C-H, C-C, C=O, and C-Cl bond lengths were corrected as described here.  Interatomic and dihedral angles, and the C-O-H geometry are those given by MP2/6-311+G(2d,p) optimization.
 
ropt(1) and ropt(2) structure parameters are given here in Z-matrix format (Gaussian 03 input file).
 
 
Table 3.  CH3-CHCl-C(=O)OH  Rotational constants (MHz).  35Cl  species.
ropt(1) ropt(2)       Expt. [1]
A 3917.8 3913.7 3895.3370(9)
B 2300.7 2350.5 2345.5558(4)
C 1782.5 1755.5 1734.0086(7)
 
 
[1] A.Lesarri, J.-U.Grabow, and W.Caminati, Chem.Phys.Lett. 468,18(2009).

 







 
Chloroacetic Acid 2-Chloropropane
 

 








Table of Contents




Molecules/Chlorine



 

 













CH3CHClCOOH.html






Last Modified 5 Jan 2009