C6H4



















 





 






Deuterium


Nuclear Quadrupole Coupling Constants


in ortho-Benzyne


 








 








Deuterium nqcc's in o-benzyne were measured by Kukolich et al. [1,2], which authors also determined a substitution molecular structure [2].   A "pseudo-re" structure was derived by Groner and Kukolich [3].

Calculation of the deuterium nqcc's was made on these molecular rs and re structures.  Calculated  nqcc's are compared with the experimental values [2] in Tables 1 and 2.  Structure parameters are given in Table 3.

 








In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor,  the 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 (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation for the B3LYP/6-31G(df,3p) model for calculation of the efg's/nqcc's.

 








 








 








Table 1.  D(3) nqcc's in o-Benzyne (kHz).  Calculation was made on rs and re molecular structures.

 










Calc /rs
Calc /re
Expt. [2]
   







Xaa
193.6
193.1
187.0(21)

Xbb
- 91.2
- 90.7
- 89.3 *

Xcc -
 102.4
 - 102.4
- 97.7 *

|Xab|
    8.3
    7.9



 







RMS
4.8 (3.8 %)
4.5 (3.6 %)



RSD
1.1 (0.9 %)
1.1 (0.9 %)



 







Xxx
- 91.5
- 90.9



Xyy -
 102.4
 - 102.4



Xzz
193.9
193.3



ETA
0.0562
0.0595



Øz,a
1.66
1.59



Øa,CD
2.35
1.46



Øz,CD
0.68
0.13



 








 








* Calculated here from experimental Xaa and Xbb - Xcc  =  8.4(44) kHz.

 








 








 








Table 2.  D(4) nqcc's in o-Benzyne (kHz).  Calculation was made on rs and re molecular structures.

 










Calc /rs
Calc /re
Expt. [2]
   







Xaa
  21.8
  26.6
  20.9(34)

Xbb
  80.2
  75.9
  77.9 *

Xcc -
 102.0
 - 102.5
- 98.8 *

|Xab|
137.7
139.6



 







RMS
2.3 (3.5 %)
4.1 (6.2 %)



RSD
1.1 (0.9 %)
1.1 (0.9 %)



 







Xxx
- 89.8
- 90.5



Xyy -
 102.0
 - 102.5



Xzz
191.8
193.0



ETA
0.0634
0.0626



Øz,a
50.98
50.01



Øa,CD
51.05
50.23



Øz,CD
  0.07
  0.22



 








 








* Calculated here from experimental Xaa and Xbb - Xcc  =  176.7(36) kHz.

 







 
 


Table 3.  o-Benzyne.  Molecular structure parameters, rs [2] and re [3] (Å and degrees).
 




  rs   re

C(1)C(2) 1.255(8)1.255(3)

C(2)C(3) 1.40(2)1.383(2)

C(3)C(4) 1.39(2)1.403(2)

C(4)C(5) 1.404(14)1.405(3)

C(3)H(3) 1.08(2)1.080(1)

C(4)H(4) 1.084(9)1.082(1)

C(1)C(2)C(3) 126(1)126.66(9)

C(2)C(3)C(4) 111(1)110.98(10)

C(3)C(4)C(5) 123(1)122.36(8)

C(2)C(3)H(3) 123(1)127.4(11)

C(5)C(4)H(4) 119(1)118.73(8)



 








 








[1] S.G.Kukolich, C.Tanjaroon, M.C.McCarthy, and P.Thaddeus, Abstract RC01, 58th Ohio State University Symposium on Molecular Spectroscopy 2003; J.Chem.Phys. 119,4353(2003).

[2] S.G.Kukolich, M.C.McCarthy, and P.Thaddeus, J.Phys.Chem. A 108,2645(2004).

[3] P.Groner and S.G.Kukolich, J.Mol.Struct. 780-781,178(2006).

 








 








Benzene-d1 Phenylacetylene-d1 Pyridine-4D

Fluorobenzene-d1


 








 








Table of Contents




Molecules/Deuterium




 








 













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Last Modified 6 Sept 2015