C9H9N




 





 






























Nitrogen


Nuclear Quadrupole Coupling Constants


in 5-Methylindole


 








 








 








The microwave spectrum of 5-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 5-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
1.722
1.695
1.728(4)

Xbb
1.704
1.704
1.664(3) *

Xcc -
 3.426
 -
 3.400
 -
 3.392(3) *

|Xab|
0.054
0.071












RMS
0.031 (1.4 %)
0.030 (1.3 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.658
1.629



Xyy
1.768
1.771



Xzz -
 3.426
 -
 3.400



ETA
0.0321
0.0417



 








 








* Derived here from experimental Xaa and Xbb - Xcc = 5.056(3) MHz.

 







 
 

Table 2.  5-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,6,B11,5,A10,4,D9,0
 H,7,B12,1,A11,6,D10,0
 H,8,B13,7,A12,1,D11,0
 H,9,B14,2,A13,1,D12,0
 C,5,B15,4,A14,3,D13,0
 H,16,B16,5,A15,4,D14,0
 H,16,B17,5,A16,4,D15,0
 H,16,B18,5,A17,4,D16,0


      B3LYP
         B3P86


 B1=1.4155961
 B2=1.39343069
 B3=1.38235341
 B4=1.41178653
 B5=1.38507822
 B6=1.43293665
 B7=1.36561975
 B8=1.37743352
 B9=1.08250692
 B10=1.08302626
 B11=1.08330541
 B12=1.07650831
 B13=1.07657521
 B14=1.00293934
 B15=1.50817296
 B16=1.09264491
 B17=1.09264491
 B18=1.08964829
 A1=121.77341424
 A2=117.66984693
 A3=122.20099961
 A4=119.32242025
 A5=134.27456377
 A6=107.13066883
 A7=107.29402091
 A8=121.49385416
 A9=118.98414996
 A10=119.89109266
 A11=127.07965654
 A12=129.92757801
 A13=125.56206607
 A14=119.57247828
 A15=111.42610065
 A16=111.42610065
 A17=111.29590344
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=180.
 D7=180.
 D8=180.
 D9=180.
 D10=0.
 D11=180.
 D12=180.
 D13=180.
 D14=-59.73240193
 D15=59.73240193
 D16=180.
  B1=1.41546289
 B2=1.39342923
 B3=1.3822325
 B4=1.41138462
 B5=1.38549834
 B6=1.43130572
 B7=1.36664373
 B8=1.37489599
 B9=1.08535344
 B10=1.08614596
 B11=1.08635252
 B12=1.07954902
 B13=1.07979078
 B14=1.00479355
 B15=1.5037349
 B16=1.09493183
 B17=1.09493183
 B18=1.09209154
 A1=121.96786976
 A2=117.51099031
 A3=122.21802675
 A4=119.43040123
 A5=134.32213189
 A6=107.02344258
 A7=107.28854941
 A8=121.56053945
 A9=119.05204104
 A10=119.85972936
 A11=127.18547279
 A12=130.0731547
 A13=125.45129001
 A14=119.55353665
 A15=111.45987846
 A16=111.45987846
 A17=111.24780513
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=180.
 D7=180.
 D8=180.
 D9=180.
 D10=0.
 D11=180.
 D12=180.
 D13=180.
 D14=-59.74485499
 D15=59.74485499
 D16=180.





 














Table 3.  5-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
 3485.5
 3483.9
 3459.1966(5)

B
 1037.0
 1039.4
 1033.90925(12)

C
   803.2
   804.5
   800.17230(5)



















[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
 2-Methylindole 3-Methylindole



4-Methylindole 6-Methylindole 7-Methylindole



 








 








Table of Contents




Molecules/Nitrogen




 








 













5MeIndole.html






Last Modified 4 May 2016