3-Cl-C4H3S






 














 






Chlorine and Sulfur


Nuclear Quadrupole Coupling Constants


in 3-Chlorothiophene


 








 


















Calculation of the chlorine nqcc's in 3-chlorothiophene was made on molecular structures obtained by B3PW91/6-31G(2d,2pd) and B3P86/6-31G(3d,3p) optimization.  Comparison of the calculated and experimental nqcc's [1] in Tables 1 and 2 suggests an error in the assignment of experimental coupling constants with respect to intertial axes.  This conclusion is strongly supported by an investigation of the microwave spectrum of the title molecule by Caminati et al. [2], wherein Xaa and Xbb respectively are reported as -73.2(5) and 38.2(3) MHz.


 








Calculated 33S 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 - 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.  (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 3-Chlorothiophene-32S (MHz).  RMS* is the root mean square difference between calculated and experimental nqcc's assuming the experimental Xbb and Xcc to be reversed (see Caminati et al. [2]).


 







Calculation was made on


the [a] B3PW91/6-31G(2d,2pd) ropt structure, and


the [b] B3P86/6-31G(3d,3p) ropt structure.
   










Calc. [a]

Calc. [b]
Expt. [1]
   








Xaa - 73.26 - 72.78 - 72.62(16)

Xbb
38.24
38.08
34.59(90)

Xcc
35.02
34.70
38.03(91)

|Xab|
  9.58
  9.63



 







RMS
2.76 (5.7 %) 2.79 (5.8 %)


RMS*
0.46 (0.96 %) 0.12 (0.25 %)


RSD
0.49 (1.1 %) 0.49 (1.1 %)


 







Xxx
39.06
38.92



Xyy
35.02
34.70



Xzz - 74.08 - 73.62



ETA - 0.054 - 0.057



z,a
4.87
4.93



a,CCl
5.16
5.22



z,CCl
0.28
0.30



 








 








 








Because B3PW91/6-31G(2d,2pd) optimization gives structures on which good agreement is obtained between calculated and experimental 33S nqcc's in thiophene and thiazole, and because  B3P86/6-31G(3d,3p) works for chlorine substituted benzenes and pyridines, as well as 2-chlorothiophene, calculation was made on a structure consisting of the B3PW91/6-31G(2d,2pd) ring with the B3P86/6-31G(3d,3p) CCl bond length.  The results are given below in Table 2 for both 35Cl and 37Cl, and in Table 3 for 33S.

 








 








   







Table 2.  Chlorine nqcc's in 3-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.  RMS* is the root mean square difference between calculated and experimental nqcc's assuming the experimental Xbb and Xcc to be reversed (see Caminati et al. [2]).
   










Calc.
Expt. [1]
   







35Cl Xaa - 72.74 - 72.62(16)


Xbb
38.07
34.59(90)


Xcc
34.67
38.03(91)


|Xab|
  9.56



 







RMS
2.79 (5.8 %)



RMS*
0.05 (0.11 %)



RSD
0.49 (1.1 %)


 







Xxx
38.89




Xyy
34.67




Xzz - 73.56




ETA - 0.057




z,a
4.90




a,CCl
5.18




z,CCl
0.28



   





37Cl Xaa - 57.36 - 57.57(16)


Xbb
30.03
27.46(75)


Xcc
27.32
30.11(76)


|Xab|
  7.37




 






RMS
2.79 (5.7 %)




RMS*
0.15 (0.40 %)




RSD
0.44 (1.1 %)




 





   








 








   








Table 3.  33S nqcc's in 3-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
- 1.93
- 1.90



Xbb - 20.30 - 20.37



Xcc
22.23
22.27



|Xab|
14.67
14.73



 







RSD
0.39 (1.7 %) 0.35 (1.5 %)


 







Xxx
  6.20
  6.25



Xyy
22.23
22.27



Xzz - 28.42
28.52



ETA
0.564
0.561



x,a
28.98
28.96



a,bi
27.79
27.79



x,bi*
  1.19
  1.17



 








 








* Angle between the x-axis and the bisector ( 'bi' ) of the CSC angle.

 








 



Table 4.  3-Chlorothiophene and Thiophene.  Structure parameters ( and degrees).
 





B3P86 B3PW91 B3PW91


X = Cl X = Cl X = H






S(1)C(2) 1.7090 1.7181 1.7197

C(2)C(3) 1.3663 1.3648 1.3660

C(3)C(4) 1.4203 1.4222 1.4229

C(4)C(5) 1.3646 1.3637 1.3660

C(5)S(1) 1.7116 1.7199 1.7197

C(2)H(2) 1.0786 1.0773 1.0787

C(3)X(3) 1.7240 1.7331 1.0816

C(4)H(4) 1.0815 1.0800 1.0816

C(5)H(5) 1.0799 1.0786 1.0787

C(5)S(1)C(2)   92.40   92.25   91.95

S(1)C(2)C(3) 110.54 110.37 111.42

C(2)C(3)C(4) 113.77 114.05 112.60

C(3)C(4)C(5) 111.40 111.50 112.60

C(4)C(5)S(1) 111.90 111.83 111.42

S(1)C(2)H(2) 121.39 121.20 119.93

S(1)C(5)H(5) 119.98 119.85 119.93

C(3)C(4)H(4) 123.88 123.69 124.04

C(4)C(3)X(3) 122.76 122.62 124.04


 








 














Table 5.  3-Chlorothiophene, normal species.  Atomic coordinates.  B3PW91/6-31G(2d,2pd) ring structure with the B3P86/6-31G(3d,3p) optimized CCl bond length.









  a ()
  b ()







S(1) - 1.9310 - 0.4933

C(2) - 0.2982 - 1.0281

C(3)
0.5516
0.0399

C(4) - 0.1038
1.3021

C(5) - 1.4602
1.1609

H(2) - 0.0546 - 2.0774

Cl(3)
2.2685 - 0.1157

H(4)
0.4177
2.2478

H(5) - 2.2130
1.9334



























Table 6.  3-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 7149.7 7184.0 7150.4 7144.19(41)
B 1503.4 1512.0 1509.9 1508.3654(31)
C 1242.2 1249.1 1246.6 1245.0304(31)



  








 








[1] Y.Niide and I.Ohkoshi, J.Mol. Spectrosc. 130,46(1988).

[2] W.Caminati, B.Velino, F.Caccinelli, R.S.Cataliotti, S.M.Murgia, G.Paliani, and S.Santucci, J.Mol.Struct. 174,285(1988): X aa and Xbb respectively are reported as -73.2(5) and 38.2(3) MHz.

 









 








Thiophene Thiazole 2-Bromothiophene

2-Chlorothiophene 3-Bromothiophene

 








 








Table of Contents




Molecules/Chlorine




Molecules/Sulfur




 








 













3ClThioph.html






Last Modified 15 Feb 2015