C2H2N2O





 





 





 





 






Nitrogen


Nuclear Quadrupole Coupling Constants


in 1,3,4-Oxdiazole


 








 








 

 





Calculation of the nitrogen nqcc's in 1,3,4-oxadiazole was made on the substitution structure of Nygaard et al. [1], and on an reSE structure derived by Demaison et al. [2].  These are nqcc's are compared with the experimental values [2] in Table 1.  Structure parameters are given in Table 2.

 








In Table 1, 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.

RMS is the root mean square difference between calculated and experiment diagonal nqcc's.  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of nitrogen nqcc's.

 








 








   








Table 1.  Nitrogen nqcc's in 1,3,4-Oxadiazole (MHz).  Calculation was made on the rs and reSE structures.

   











Calc/rs
Calc/reSE
Expt [2]
   








14N Xaa - 3.635 -
 3.734
 -
 3.7584(13)


Xbb
1.835
1.935
2.01835(93)


Xcc
1.800
1.799
1.74007(87)


Xab ± 2.755 ± 2.712
 ± 2.43(12)

 









RMS
0.132 (5.3 %)
0.061 (2.4 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)



 









Xxx
2.982
3.023
2.909(83)


Xyy
1.800
1.799
1.74007(87)

  Xzz - 4.782 -
 4.822
 -
 4.649(83)

  ETA - 0.247 -
 0.254




Øz,a
22.6
21.86




Øa,bi
33.3
37.22




Øz,bi *
10.7
15.36



 









 








* The z-axis makes an angle of 10.7o/15.4o with the external bisector ('bi') of the CNN angle and tilts toward the adjacent N.

 







 
 


Table 2.  1,3,4-Oxadiazole.  Molecular structure parameters (Å and degrees).
 


 
rs [1]reSE (IRLS) [2]

OC 1.3481.3537(15)

CN 1.2971.2853(18)

NN 1.3991.4056(30)

CH 1.0751.0729(13)

COC 102.0101.38(11)

OCN 113.4113.76(14)

CNN 105.6105.55(11)

OCH 118.1118.46(83)



 








 








[1] L.Nygaard, R.L.Hansen, J.T..Nielsen, J.Rastrup-Andersen, G.O.Sørensen, and P.A.Steiner, J.Mol.Struct. 12,59(1972); M.D.Harmony, V.W.Laurie, R.L.Kuczkowski, R.H.Schwendeman, D.A.Ramsay, F.J.Lovas, W.J.Lafferty, and A.G.Maki, J.Phys.Chem.Ref.Data 8,619(1979).

[2] J.Demaison, M.K.Jahn, E.J.Cocinero, A.Lesarri, J.-U.Grabow, J.-C.Guillemin, and H.D.Rudolph J.Phys.Chem. A 117,2278(2013).

 








 








Oxazole 1,2,5-Oxadiazole 1,2,3-Thiadiazole

1,2,4-Thiadiazole 1,2,5-Thiadiazole 1,3,4-Thiadiazole

 








 








Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 21 Feb 2013