2-Cl-C4H3S




 





 
 

Chlorine and Sulfur

Nuclear Quadrupole Coupling Constants


in 2-Chlorothiophene


 







 
Calculation of the chlorine nqcc's in 2-chlorothiophene was made on molecular structures obtained by B3PW91/6-31G(2d,2pd) and B3P86/6-31G(3d,3p) optimization, and on the B3PW91 structure but with the CCl bond length of the B3P86 optimization.  Sulfur nqcc's were calculated on this last structure.
 
Calculated chlorine nqcc's are compared with the experimental values [1] in Tables 1 and 2.  Calculated sulfur nqcc's are given in Table 3.  Structure parameters are given in Table 4, atomic coordinates in Table 5, and rotational constants in Table 6.
 
In Tables 1 and 3, 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 nqcc's (percent of average absolute experimental nqcc).  RSD is the residual standard deviation of calibration of the model for calculation of the nqcc's.
 
 
   






Table 1.  35Cl nqcc's in 2-Chlorothiophene-32S (MHz).
 
Calculation was made on
the [a] B3PW91/6-31G(2d,2pd) opt structure, and
the [b] B3P86/6-31G(3d,3p) opt structure.
   







Calc. [a]
Calc. [b]
Expt. [1]
   





Xaa - 75.44 - 74.92 - 74.77(5)
Xbb 38.49 38.30 37.51(17)
Xcc 36.94 36.62 37.25(18)
|Xab| 10.20   9.99
 
RMS 0.71 (1.4 %) 0.59 (1.2 %)
RSD 0.49 (1.1 %) 0.49 (1.1 %)
 
Xxx 39.40 39.17
Xyy 36.94 36.62
Xzz - 76.34 - 75.79
ETA - 0.032 - 0.034
Øz,a 5.08 5.00
Øa,CCl 6.10 6.04
Øz,CCl 1.02 1.03
 
 
 
   






Table 2.  Chlorine nqcc's in 2-Chlorothiophene-32S (MHz).  Calculation was made on the B3PW91/6-31G(2d,2pd) ring structure with the B3P86/6-31G(3d,3p) optimized CCl bond length.
   









Calc.
Expt. [1]
   





35Cl Xaa - 74.86 - 74.77(5)
Xbb 38.29 37.51(17)
Xcc 36.58 37.25(18)
|Xab| 10.14
 
RMS 0.60 (1.2 %)
RSD 0.49 (1.1 %)
 
Xxx 39.19
Xyy 36.58
Xzz - 75.76
ETA - 0.034
Øz,a 5.08
Øa,CCl 6.11
Øz,CCl 1.03
   
37Cl Xaa - 58.98 - 58.98(9)
Xbb 30.16 29.55(26)
Xcc 28.82 29.43(28)
|Xab|   8.08
 
RMS 0.50 (1.2 %)
RSD 0.44 (1.1 %)
 
   
 
   






Table 3.  33S nqcc's in 2-Chlorothiophene-35Cl (MHz).  Calculation was made on the B3PW91/6-31G(2d,2pd) ring structure with the B3P86/6-31G(3d,3p) optimized CCl bond length.
Calc. [a] B3LYP/6-311G(3df,3p) Model.
Calc. [b] B3LYP/TZV+(3df,3p) Model.
   







Calc. [a]
Calc. [b]
Expt.
   





Xaa - 27.96 - 28.04
Xbb   3.56   3.67
Xcc 24.40 24.37
|Xab|   7.84   7.84
 
RSD 0.39 (1.7 %) 0.35 (1.5 %)
 
Xxx   5.40   5.50
Xyy 24.40 24.37
Xzz - 29.80 - 29.88
ETA 0.638 0.632
Øx,a 76.77 76.84
Øa,bi 81.33 81.33
Øx,bi*   4.56   4.49
 
 
* The x-axis makes an angle of 4.56o / 4.49o with the external bisector ( 'bi' ) of the C(5)S(1)C(2) and tilts toward C(2).
 
 
Table 4.  2-Chlorothiophene and Thiophene.  Structure parameters (Å and degrees).
 
B3P86 B3PW91 B3PW91
X = Cl X = Cl X = H
S(1)C(2) 1.7195 1.7269 1.7197
C(2)C(3) 1.3658 1.3652 1.3660
C(3)C(4) 1.4205 1.4225 1.4229
C(4)C(5) 1.3656 1.3653 1.3660
C(5)S(1) 1.7149 1.7232 1.7197
C(2)X(2) 1.7116 1.7205 1.0787
C(3)H(3) 1.0815 1.0901 1.0816
C(4)H(4) 1.0825 1.0812 1.0816
C(5)H(5) 1.0799 1.0786 1.0787
C(5)S(1)C(2)   91.29   91.08   91.95
S(1)C(2)C(3) 112.37 112.41 111.42
C(2)C(3)C(4) 111.63 111.70 112.60
C(3)C(4)C(5) 112.91 113.08 112.60
C(4)C(5)S(1) 111.79 111.74 111.42
S(1)C(2)X(2) 120.61 120.50 119.93
S(1)C(5)H(5) 119.65 119.50 119.93
C(3)C(4)H(4) 123.77 123.56 124.04
C(4)C(3)H(3) 125.18 125.13 124.04
 
 
Table 5.  2-Chlorothiophene, normal species.  Atomic coordinates.  B3PW91/6-31G(2d,2pd) ring structure with the B3P86/6-31G(3d,3p) optimized CCl bond length.
  a (Å)   b (Å)
S(1) - 0.6668 - 1.1580
C(2) 0.3632 0.2280
C(3) - 0.3393 1.3986
C(4) - 1.7432 1.1695
C(5) - 2.0690 - 0.1564
Cl(2) 2.0651 0.0457
H(3) 0.1318 2.3706
H(4) - 2.4782 1.9624
H(5) - 3.0468 - 0.6115

Table 6.  2-Chlorothiophene, normal species.  Rotational Constants (MHz).
   
[a] B3PW91/6-31G(2d,2pd) opt structure.
[b] B3P86/6-31G(3d,3p) opt structure.
[c] B3PW91/6-31G(2d,2pd) ring structure with the B3P86/6-31G(3d,3p) optimized CCl bond length.
 
Calc [a] Calc [b] Calc [c] Expt. [1]
A 5395.3 5423.0 5395.3 5396.039(25)
B 1865.0 1877.8 1873.8 1875.224(2)
C 1385.9 1394.8 1390.7 1391.162(2)


  







 
[1] J.Mjöberg and S.Ljunggren, Z.Naturforsch. 28a,729(1973).
 

 







Thiophene Thiazole 2-Bromothiophene
3-Chlorothiophene 3-Bromothiophene
 

 








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Molecules/Chlorine
Molecules/Sulfur
 

 













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Last Modified 8 Oct 2004