1,2-Dichlorobenzene

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Chlorine


Nuclear Quadrupole Coupling Constants


in 1,2-Dichlorobenzene


 







 
 
35Cl nqcc's in 1,2-dichlorobenzene were first determined by Onda and Yamaguchi [1], and revisited by Merke et al. [2].  An effective molecular structure was determined by Onda et al. [3].
 
Chlorine nqcc's were calculated here on the molecular structure of Onda et al., and on a structure given by B3P86/6-31G(3d,3p) optimization.  These calculated nqcc's are compared with the experimental values in Tables 1 and 2.  The structure parameters are compared in Table 3.  In Table 4, atomic coordinates for the optimized structure are given.
 
In Table 1, 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 for the B1LYP/TZV(3df,2p) model for calculation of the chlorine nqcc's. 
 
Subscripts a,b,c refer to the principal axes of the inertia tensor; 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 molecular plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

 







 
 
   







Table 1. Chlorine nqcc's in 1,2-Dichlorobenzene (MHz).  Calculation was made on the ro molecular structure of Onda et al. [3].
   










Calc.
Expt. [2]
   






35Cl Xaa - 41.49 - 41.1153(35)
Xbb   8.85   8.3415(96)
Xcc 32.64 32.7738(61)
Xab ± 52.24 ± 52.41(58)
 
RMS 0.37 (1.4 %)
RSD 0.49 (1.1 %)
 
Xxx 41.67 41.57(52)
Xyy 32.64 32.7738(61)
Xzz - 74.31 - 74.34(52)
ETA - 0.122 - 0.118
Øz,a 32.14 32.4
Øa,CCl 30.90 30.9
Øz,CCl   1.24   1.5
   
37Cl Xaa - 32.70
Xbb   6.98
Xcc 25.72
Xab ± 41.18
 
RSD 0.44 (1.1 %)
 

 
 
   







Table 2. Chlorine nqcc's in 1,2-Dichlorobenzene (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
   










Calc.
Expt. [2]
   






35Cl Xaa - 40.95 - 41.1153(35)
Xbb   8.41   8.3415(96)
Xcc 32.54 32.7738(61)
Xab ± 52.34 ± 52.41(58)
 
RMS 0.17 (0.63 %)
RSD 0.49 (1.1 %)
 
Xxx 41.60 41.57(52)
Xyy 32.54 32.7738(61)
Xzz - 74.14 - 74.34(52)
ETA - 0.122 - 0.118
Øz,a 32.38 32.4
Øa,CCl 31.17
Øz,CCl   1.21
   
37Cl Xaa - 32.27
Xbb   6.63
Xcc 25.64
Xab ± 41.25
 
RSD 0.44 (1.1 %)
 
 
The nqcc z-axis makes an angle of 1.21o with the CCl bond axis.  In 1,2-chlorofluorobenzene, this angle is 1.07o.  On the other hand, in 1,3-dichlorobenzene and 1,3-chlorofluorobenzene, this angle is 0.09o and 0.06o respectively.  (Calculated nqcc's, ropt structures.)
 
 
Table 3.  Molecular structure parameters  (Å and degrees).
 
ro [1]   ropt
C(1,2)Cl(1,2) 1.729 1.7251

C(1)C(2) 1.398 1.3969
C(2)C(3) 1.393 1.3916
C(3)C(4) 1.397 1.3874
C(4)C(5) 1.394 1.3897
C(3)H(3) 1.083 1.0833
C(4)H(4) 1.080 1.0843
C(1)C(2)C(3) 120.3 119.78
C(2)C(3)C(4) 119.5 120.16
C(3)C(4)C(5) 120.3 120.05
C(1)C(2)Cl(2) 120.9 121.17
C(2)C(3)H(3) 118.7 118.78
C(3)C(4)H(4) 119.5 119.56
 
For comparison with the optimized structure,  the B3P86/6-31G(3d,3p) optimized structure of benzene is CC = 1.3909 Å and CH = 1.0851 Å.
 
 
Table 4. Atomic Coordinates, ropt
(More figures are shown than are significant.)
  a (Å)   b (Å)
Cl(1,2) - 1.426031 ± 1.591375
C(1,2) 0.050003 ± 0.698460
C(3,6) 1.257799 ± 1.389658
C(4,5) 2.458660 ± 0.694872
H(3,6) 1.238906 ± 2.472784
H(4,5) 3.393972 ± 1.243330
 
 

[1] M.Onda and I.Yamaguchi, J.Mol.Struct. 34,1(1976).
[2] I.Merke, Ch.Keussen, H.Dreizler, and M.Onda, Z.Naturforsch. 45a,1273(1990).
[3] M.Onda, M.Ueda, M.Atsuki, J.Yamaguchi, and I.Yamaguchi, J.Mol.Struct. 147,77(1986).

 







 

Chlorobenzene 1,2-Chlorofluorobenzene

1,3-Dichlorobenzene 1,3-Chlorofluorobenzene
1,4-Dichlorobenzene 1,4-Chlorofluorobenzene
cis-2-Chlorophenol trans-2-Chlorophenol
 

 








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Last Modified 4 June 2003