Oxazole





 






 

































Nitrogen


Nuclear Quadrupole Coupling Constants


in Oxazole


 








 








 

 





Kumar, Sheridan, and Stiefvater [1,2] determined the nitrogen nqcc's in oxazole and monodeuterated oxazole, and derived the complete substitution molecular structure.

 








Calculation was made here of the nitrogen nqcc's on this rs structure.  These nqcc's are compared in Tables 1 - 4 with the experimental values.  Structure parameters are given in Table 5.

 








In Tables 1 - 4, 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 experimental nqcc's (percentage of the average of the magnitudes of the experimental 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.  14N nqcc's in Oxazole (MHz).  Calculation was made on the rs structure of Kumar et al. [2].
 










Calc.
Expt. [1,2]
Expt. [3]
 








Xaa - 3.986 - 3.92(2) -
 3.99

Xbb
1.571
1.54(2)
1.58

Xcc
2.414
2.38
2.41

|Xab|
0.908
0.81












RMS


0.05 (1.8 %)
0.003 (0.1 %)

RSD


0.030 (1.3 %)
0.030 (1.3 %)











 








 








   






Table 2.  Nitrogen nqcc's in 2-d1-Oxazole (MHz).  Calculation was made on the rs structure of Kumar et al. [2].
   









Calc.
Expt. [1,2]
   






14N Xaa
1.192
1.22(2)


Xbb - 3.606 - 3.60(2)


Xcc
2.414
2.38


|Xab|
1.670
1.52

 







RMS
0.03 (1.1 %)
 


RSD
0.030 (1.3 %)



 







Xxx
1.716
1.66(2)


Xyy
2.414
2.38

  Xzz - 4.130 - 4.04(2)

  ETA
0.169




Øz,a
72.58




Øa,bi
67.69




Øz,bi *
  4.89
  5.7

 







 








* The z-axis makes an angle of 4.89o (5.7o) with the external bisector ('bi') of the C(2)N(3)C(4) angle and tilts toward C(4).

 








 








   






Table 3.  Nitrogen nqcc's in 4-d1-Oxazole (MHz).  Calculation was made on the rs structure of Kumar et al. [2].
   









Calc.
Expt. [1,2]
   






14N Xaa - 0.371 - 0.37(5)


Xbb - 2.044 - 2.01(5)


Xcc
2.414
2.38


|Xab|
2.801
2.74

 







RMS
0.03 (1.7 %)
 


RSD
0.030 (1.3 %)



 







 








 








   






Table 4.  Nitrogen nqcc's in 5-d1-Oxazole (MHz).  Calculation was made on the rs structure of Kumar et al. [2].
   









Calc.
Expt. [1,2]
   






14N Xaa - 3.173 - 2.98(5)


Xbb
0.759
0.60(5)


Xcc
2.414
2.38


|Xab|
2.163
2.19

 







RMS
0.14 (7.3 %)
 


RSD
0.030 (1.3 %)



 







 







 
 

Table 5. Molecular structure parameters, rs [2] (Å and degrees).
 


O(1)C(2) 1.3574

C(2)N(3) 1.2915
Z-Matrix N(3)C(4) 1.3954

C(4)C(5) 1.3525

C(5)O(1) 1.3696

C(2)H(2) 1.0750

C(4)H(4) 1.0751

C(5)H(5) 1.0732

C(5)O(1)C(2) 103.91

O(1)C(2)N(3) 114.99

C(2)N(3)C(4) 103.92

N(3)C(4)C(5) 109.04

C(4)C(5)O(1) 108.14

O(1)C(2)H(2) 117.09

N(3)C(4)H(4) 121.89

O(1)C(5)H(5) 116.86



 








 








[1] A.Kumar, J.Sheridan, and O.L.Stiefvater, Z.Naturforsch. 33a,549(1978).

[2] A.Kumar, J.Sheridan, and O.L.Stiefvater, Z.Naturforsch. 33a,145(1978).

[3] W.C.Mackrodt, A.Wardley, P.A.Curnuck, N.L.Owen, and J.Sheridan, Chem.Comm. (Loudon) 692(1966).

 








 








Isoxazole Imidazole Thiazole Pyrazole

 








 








Table of Contents




Molecules/Nitrogen




 








 













Oxazole.html






Last Modified 6 Nov 2003