CH3-C4NH3-CH3
























 





 









Nitrogen


Nuclear Quadrupole Coupling Constants


in 2,5-Dimethylpyrrole


 








 








 








Calculation was made here of the nitrogen nqcc's in 2,5-dimethylpyrrole on a molecular structure given by B3LYP/cc-pVTZ optimization.  These calculated nqcc's are compared with the experimental values of Nguyen et al. [1] in Table 1.  Structure parameters are given in Z-matrix format in Table 2, rotational constants in Table 3.

 








In Table 1, the 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 nqcc's (percent of the average experimental value).  RSD is the calibration residual standard deviation of the (1) B3PW91/6-311+G(df,pd) and (2) B3PW91/6-311+G(d,p) models for calculation of nitrogen efg's/nqcc's.

 








 








 








Table 1.  14N nqcc's in 2,5-Dimethylpyrrole (MHz).  Calculation was made on the B3LYP/cc-pVTZ optimized structure with both (1) B3PW91/6-311+G(df,pd) and (2) B3PW91/6-311+G(d,p) models.
 










Calc (1)
Calc (2)
Expt. [1]
 








Xaa
1.302
1.384
1.3267(20)

Xbb - Xcc
4.737
4.986
4.6382(29)

Xbb
1.717
1.801
1.6557 *

Xcc -
 3.020 -
 3.185
 -
 2.9824 *










RMS
0.044 (2.2 %)
0.148 (7.4 %)



RSD
0.030 (1.3 %)
0.086 (3.8 %)












Xxx
1.302
1.384



Xyy
1.717
1.801



Xzz - 3.020 -
 3.185



ETA
0.137
0.131



Øz,c
  0
  0













 








*Calculated here from Xaa and Xbb - Xcc

 







 



Table 2.  2,5-Dimethylpyrrole.  Molecular structure parameters, ropt = B3LYP/cc-pVTZ optimization (Å and degrees).  
 

 N
 C,1,B1
 C,1,B2,2,A1
 C,2,B3,1,A2,3,D1,0
 C,3,B4,1,A3,2,D2,0
 H,1,B5,2,A4,4,D3,0
 H,4,B6,2,A5,1,D4,0
 H,5,B7,3,A6,1,D5,0
 C,3,B8,1,A7,2,D6,0
 H,9,B9,3,A8,1,D7,0
 H,9,B10,3,A9,1,D8,0
 H,9,B11,3,A10,1,D9,0
 C,2,B12,1,A11,3,D10,0
 H,13,B13,2,A12,1,D11,0
 H,13,B14,2,A13,1,D12,0
 H,13,B15,2,A14,1,D13,0
      Variables:
 B1=1.37775463
 B2=1.37775463
 B3=1.37296715
 B4=1.37296715
 B5=1.00450533
 B6=1.07726677
 B7=1.07726677
 B8=1.4907549
 B9=1.09393253
 B10=1.09393253
 B11=1.08856205
 B12=1.4907549
 B13=1.09393253
 B14=1.09393253
 B15=1.08856205
 A1=110.78802651
 A2=106.71235221
 A3=106.71235221
 A4=124.60598675
 A5=125.31482638
 A6=125.31482638
 A7=121.96764407
 A8=112.14237908
 A9=112.14237908
 A10=109.88979051
 A11=121.96764407
 A12=112.14237908
 A13=112.14237908
 A14=109.88979051
 D1=0.
 D2=0.
 D3=180.
 D4=180.
 D5=180.
 D6=180.
 D7=-60.46372618
 D8=60.46372618
 D9=180.
 D10=180.
 D11=-60.46372618
 D12=60.46372618
 D13=180.


 













Table 3.  2,5-Dimethylpyrrole.  Rotational constants (MHz).  Calc = B3LYP/cc-pVTZ opt
 



 
     Calc.
    XIAM [1]






A      6345.
 6290.61877(82)

B      2018.
 2016.95974(17)

C      1561.
 1557.07320(16)






















[1] T.Nguyen, C.Dindic, W.Stahl, H.V.L.Nguyen, and I.Kleiner, Poster, HRMS Dijon 2019.

 








 








Pyrrole




 








 








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Molecules/Nirogen




 








 













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Last Modified 28 Nov 2019