C9H9N




 





 






























Nitrogen


Nuclear Quadrupole Coupling Constants


in 2-Methylindole


 








 








 








The microwave spectrum of 2-methylindole was assigned by Gurusinghe and Tubergen [1,2].

 








Calculation of the 14N nqcc tensor was made here on ropt molecular structures given by B3LYP/cc-pVTZ and B3P86/6-31G(3d,3p) optimization.  Calculated and experimental nqcc's are compared in Table 1.  Structure parameters are given in Z-matrix format in Table 2, rotational constants in Table 3.

 








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.  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-Methylindole (MHz).  Calculation was made on molecular structures given by (1) B3LYP/cc-pVTZ and (2) B3P86/6-31G(3d,3p) optimization.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa
1.728
1.692
1.74(5)

Xbb
1.829
1.835
1.76(3) *

Xcc -
 3.557
 -
 3.527
 -
 3.50(3) *

|Xab|
0.066
0.278












RMS
0.056 (2.4 %)
0.057 (2.4 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.695
1.657



Xyy
1.862
1.870



Xzz -
 3.557
 -
 3.527



ETA
0.0468
0.0602



 








 








* Derived here from experimental Xaa and Xbb - Xcc = 5.25(3) MHz.

 







 
 

Table 2.  2-Methylindole.  Optimized molecular structure parameters, ropt (Å and degrees).
 

B3LYP/cc-pVTZ  and  B3P86/6-31G(3d,3p)
 



 C
 C,1,B1
 C,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 C,4,B4,3,A3,2,D2,0
 C,5,B5,4,A4,3,D3,0
 C,1,B6,6,A5,5,D4,0
 C,7,B7,1,A6,6,D5,0
 N,2,B8,1,A7,6,D6,0
 H,3,B9,2,A8,1,D7,0
 H,4,B10,3,A9,2,D8,0
 H,5,B11,4,A10,3,D9,0
 H,6,B12,5,A11,4,D10,0
 H,7,B13,1,A12,6,D11,0
 H,9,B14,2,A13,1,D12,0
 C,8,B15,7,A14,1,D13,0
 H,16,B16,8,A15,7,D14,0
 H,16,B17,8,A16,7,D15,0
 H,16,B18,8,A17,7,D16,0


      B3LYP
         B3P86


 B1=1.41763846
 B2=1.39201945
 B3=1.38582293
 B4=1.40372442
 B5=1.38420653
 B6=1.43353383
 B7=1.367588
 B8=1.37820966
 B9=1.08250307
 B10=1.08172812
 B11=1.08183338
 B12=1.08240385
 B13=1.07707892
 B14=1.00366679
 B15=1.48966932
 B16=1.09344023
 B17=1.09344023
 B18=1.0880166
 A1=122.30846539
 A2=117.56426432
 A3=121.12756287
 A4=121.11831628
 A5=134.52387425
 A6=107.80143532
 A7=107.01477976
 A8=121.44016278
 A9=119.43175635
 A10=119.1862736
 A11=120.46449139
 A12=126.9019671
 A13=125.29929244
 A14=130.38746536
 A15=111.67171181
 A16=111.67171181
 A17=110.13782167
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=180.
 D7=180.
 D8=180.
 D9=180.
 D10=180.
 D11=0.
 D12=180.
 D13=180.
 D14=119.8376394
 D15=-119.8376394
 D16=0.
  B1=1.41758756
 B2=1.39206116
 B3=1.3856695
 B4=1.40357559
 B5=1.38417346
 B6=1.43139519
 B7=1.36883298
 B8=1.37502923
 B9=1.08537312
 B10=1.08481225
 B11=1.08489446
 B12=1.08532266
 B13=1.08015147
 B14=1.0054906
 B15=1.48641009
 B16=1.09553869
 B17=1.09553869
 B18=1.09029993
 A1=122.43432839
 A2=117.42077156
 A3=121.19804969
 A4=121.16765778
 A5=134.5319179
 A6=107.66210557
 A7=107.05462413
 A8=121.49847894
 A9=119.37995462
 A10=119.17692234
 A11=120.50989008
 A12=127.10469023
 A13=125.27931911
 A14=130.35975629
 A15=111.76191149
 A16=111.76191149
 A17=109.98136492
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=180.
 D7=180.
 D8=180.
 D9=180.
 D10=180.
 D11=0.
 D12=180.
 D13=180.
 D14=119.76054181
 D15=-119.76054181
 D16=0.





 














Table 3.  2-Methylindole.  Rotational Constants (MHz).







ropt(1) = B3LYP/cc-pVTZ optimization.

ropt(2) = B3P86/6-31G(3d,3p) optimization.








ropt(1) ropt(2) Expt [1]







A
 3822.4
 3818.2
 3790.6183(13)

B
   993.0
   995.4
   990.2520(3)

C
   792.1
   793.5
   789.2286(2)



















[1] R.Gurusinghe and M.Tubergen, J.Chem.Phys. A 120(20),3491(2016).

[2] R.Gurusinghe and M.Tubergen, Abstract RJ03, 69th International Symposium on Molecular Spectroscopy, Champaign-Urbana, Ill. 2014.

 








 








Indole
Pyrrole N-Methylpyrrole
 Carbazole

1-Methylindole
 3-Methylindole 5-Methylindole



4-Methylindole
 6-Methylindole 7-Methylindole



 








 








Table of Contents




Molecules/Nitrogen




 








 













2MeIndole.html






Last Modified 4 May 2016