2-CH3-C5H5NO















 









Nitrogen


Nuclear Quadrupole Coupling Constants

in 2-Methylpyridine-N-oxide

 








 








Nitrogen nqcc's in 2-methylpyridine-N-oxide were determined by Heineking et al. [1].  Calculation of the nqcc's was made on B3P86/6-31G(3d,3p) optimized structures of conformers I and II shown below.  These calculated nqcc's are compared with experimental values in Table 1.  Structure parameters are given in Z-matrix format in Table 2, rotational constants in Table 3.

 








Conformer I

Conformer II




































At the B3PW91/6-311+G(df,pd) level of theory, II is more stable than I by 7.8 kJ/mol.

 








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.  ETA = (Xxx - Xyy)/Xzz.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average magnitude 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 efg's/nqcc's.

 








 








 








Table 1.  14N nqcc's in 2-Methylpyridine-N-oxide (MHz).  Calculation was made on B3P86/6-31G(3d,3p) optimized structures of both conformers I and II.
 










Calc I
Calc II
  Expt. [1]
 








Xaa
0.372
0.472
0.443(10)

Xbb
 -
 0.177
 -
 0.231
 -
 0.240(7)

Xcc -
 0.195
 -
 0.241
 -
 0.203(14)

|Xab|
0.765
0.758












RMS
0.055 (18.6 %)
0.028 (9.6 %)
 

RSD
0.030 (1.3 %)
0.030 (1.3 %)












Xxx -
 0.195
 -
 0.241



Xyy -
 0.716
 -
 0.715



Xzz
0.911
0.956



ETA
0.572
0.495













 








 
















Table 2.  2-Methylpyridine-N-oxide.  B3P86/6-31G(3d,3p) Structure parameters (Å and degrees).









 N
 O,1,B1
 C,1,B2,2,A1
 C,1,B3,2,A2,3,D1,0
 C,3,B4,1,A3,2,D2,0
 C,4,B5,1,A4,2,D3,0
 C,5,B6,3,A5,1,D4,0
 H,3,B7,1,A6,2,D5,0
 H,5,B8,3,A7,1,D6,0
 H,6,B9,4,A8,1,D7,0
 H,7,B10,5,A9,3,D8,0
 C,4,B11,1,A10,2,D9,0
 H,12,B12,4,A11,1,D10,0
 H,12,B13,4,A12,1,D11,0
 H,12,B14,4,A13,1,D12,0



















Conformer I
 Conformer II









 B1=1.27023688
 B2=1.36629998
 B3=1.37773941
 B4=1.3753252
 B5=1.38616575
 B6=1.38977479
 B7=1.08102797
 B8=1.08364148
 B9=1.0848803
 B10=1.08304489
 B11=1.4911362
 B12=1.09353125
 B13=1.09353125
 B14=1.08881994
 A1=119.36323879
 A2=121.45867002
 A3=122.09314831
 A4=119.11148869
 A5=119.83722449
 A6=113.00550159
 A7=118.51976834
 A8=117.35555525
 A9=121.30849558
 A10=117.16641119
 A11=110.65549339
 A12=110.65549339
 A13=109.39727468
 D1=180.
 D2=180.
 D3=180.
 D4=0.
 D5=0.
 D6=180.
 D7=180.
 D8=180.
 D9=0.
 D10=120.3513384
 D11=-120.3513384
 D12=0.
  B1=1.27026762
 B2=1.36426869
 B3=1.3744287
 B4=1.37649486
 B5=1.38507983
 B6=1.38771274
 B7=1.08109225
 B8=1.08362645
 B9=1.08435563
 B10=1.08306838
 B11=1.4841463
 B12=1.09380545
 B13=1.09380545
 B14=1.09046205
 A1=120.39541482
 A2=120.02054338
 A3=121.61881918
 A4=119.34961023
 A5=121.57309288
 A6=113.29019357
 A7=118.55257511
 A8=117.67939284
 A9=120.90863217
 A10=115.33404511
 A11=110.4275853
 A12=110.4275853
 A13=110.44434817
 D1=180.
 D2=180.
 D3=180.
 D4=0.
 D5=0.
 D6=180.
 D7=180.
 D8=180.
 D9=0.
 D10=-58.36208218
 D11=58.36208218
 D12=180.










 














Table 3.  2-Methylpyridine-N-oxide.  Calculated and experimental rotational constants (MHz).








     I     II    Expt [1]







A
   3484.
   3562.
 3524.9512(3)

B
   2304.
   2293.
 2278.3924(2)

C
   1399.
   1407.
 1395.7957(2)









 








 








[1] N.Heineking, H.Dreizler, K.Endo, and Y.Kamura, Z.Naturforsch. 44a,1196(1989).

 








 








Pyridine
 Pyridine-N-oxide


 








 








Table of Contents




Molecules/Nitrogen




 








 













2MePyridineNO.html






Last Modified 9 Dec 2015