C9H9N




 





 






























Nitrogen


Nuclear Quadrupole Coupling Constants


in 4-Methylindole


 








 








 








The microwave spectrum of 4-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 4-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
1.729
1.713
1.699(5)

Xbb
1.685
1.676
1.647(5)

Xcc -
 3.414
 -
 3.390
3.346(5)

|Xab|
0.049
0.067












RMS
0.048 (2.2 %)
0.032 (1.4 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.654
1.625



Xyy
1.761
1.764



Xzz -
 3.414
 -
 3.390



ETA
0.0314
0.162



 








 








* Derived here from experimental Xaa and Xbb - Xcc = 4.993(8) MHz.

 







 
 

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


      B3LYP
         B3P86


 B1=1.41973622
 B2=1.39257468
 B3=1.38361257
 B4=1.40272614
 B5=1.38798782
 B6=1.4361605
 B7=1.36388915
 B8=1.37609272
 B9=1.08209916
 B10=1.08183128
 B11=1.07592154
 B12=1.07651152
 B13=1.00298665
 B14=1.08334615
 B15=1.50699398
 B16=1.09212147
 B17=1.09212147
 B18=1.08829323
 A1=122.52987665
 A2=117.01517358
 A3=121.27675066
 A4=122.26254003
 A5=133.86469443
 A6=107.25486028
 A7=107.25245507
 A8=121.65315671
 A9=119.51080735
 A10=127.47144846
 A11=129.92142155
 A12=125.37699279
 A13=118.71109626
 A14=120.92122536
 A15=111.12258596
 A16=111.12258596
 A17=111.92392176
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=180.
 D7=180.
 D8=180.
 D9=0.
 D10=180.
 D11=180.
 D12=180.
 D13=180.
 D14=-59.61336714
 D15=59.61336714
 D16=180.
  B1=1.41892659
 B2=1.39248842
 B3=1.38385929
 B4=1.40248887
 B5=1.38823659
 B6=1.43385094
 B7=1.36509965
 B8=1.37388271
 B9=1.0849851
 B10=1.08491856
 B11=1.07927348
 B12=1.07972128
 B13=1.0048088
 B14=1.08639434
 B15=1.50245437
 B16=1.09433713
 B17=1.09433713
 B18=1.09107479
 A1=122.63132815
 A2=116.9124712
 A3=121.31837739
 A4=122.25863797
 A5=133.79125666
 A6=107.12141164
 A7=107.22179314
 A8=121.70992011
 A9=119.47330341
 A10=127.5686892
 A11=130.07494229
 A12=125.28495066
 A13=118.81304843
 A14=121.03268059
 A15=111.19221461
 A16=111.19221461
 A17=111.78218202
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=180.
 D7=180.
 D8=180.
 D9=0.
 D10=180.
 D11=180.
 D12=180.
 D13=180.
 D14=-59.65588572
 D15=59.65588572
 D16=180.





 














Table 3.  4-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
 2182.
 2184.
 2164.6596(6)

B
 1481.
 1484.
 1484.9238(4)

C
   887.
   888.
   885.7763(9)









 








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

[2] R.Gurusinghe and M.Tubergen, Abstract WF08, 71st International Symposium on Molecular Spectroscopy, Champaign-Urbana, Ill. 2016.

 








 








Indole
Pyrrole N-Methylpyrrole
 Carbazole

3-Methylindole
 2-Methylindole 5-Methylindole 1-Methylindole

6-Methylindole 7-Methylindole




 








 








Table of Contents




Molecules/Nitrogen




 








 













4MeIndole.html






Last Modified 4 May 2016