C8H7N




 





 






























Nitrogen


Nuclear Quadrupole Coupling Constants


in Indole


 








 








 








The microwave spectrum of indole, including determination of 14N diagonal quadrupole coupling constants, was first investigated by Suenram et al. [1], and revisited by Nesvadba et al. [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 Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants and electric dipole moments in Table 4, and quartic centrifugal distortion constants in Table 5.

 








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.  Ř (degrees) is the angle between its subscripted parameters.

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 Indole (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
1.696
1.667
1.7263(43)

Xbb
1.722
1.727
1.6525(50)

Xcc -
 3.418
 -
 3.394
 -
 3.3788(48)

|Xab|
0.048
0.059












RMS
0.049 (2.2 %)
0.056 (2.5 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 








 








 








   







Table 2.  14N nqcc's in Indole (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. [2]
   







Xaa
1.696
1.667
1.72983(82)

Xbb
1.722
1.727
1.65668(85)

Xcc -
 3.418
 -
 3.394
 -
 3.38651(85)

|Xab|
0.048
0.059












RMS
0.046 (2.0 %)
0.055 (2.4 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.659
1.630



Xyy
1.759
1.763



Xzz -
 3.418
 -
 3.394



ETA
0.0293
0.0392



Řb,NH
18.30
18.16



Řx,NH
70.53
75.57



Řy,NH
19.47
13.43



 








 







 
 

Table 3.  Indole.  Optimized molecular structure parameters, ropt (Ĺ 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,1,B5,2,A4,3,D3,0
 C,1,B6,6,A5,5,D4,0
 C,7,B7,1,A6,6,D5,0
 N,8,B8,7,A7,1,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,B12,1,A11,2,D10,0
 H,7,B13,1,A12,6,D11,0
 H,8,B14,7,A13,1,D12,0
 H,9,B15,8,A14,7,D13,0


      B3LYP
         B3P86


 B1=1.41870588
 B2=1.39371179
 B3=1.38398127
 B4=1.40527917
 B5=1.40115176
 B6=1.43319672
 B7=1.36471987
 B8=1.37861464
 B9=1.08235476
 B10=1.08165221
 B11=1.08173831
 B12=1.08228723
 B13=1.07643318
 B14=1.07646841
 B15=1.00303055
 A1=122.27339579
 A2=117.54113941
 A3=121.18448136
 A4=118.74158588
 A5=134.39823704
 A6=107.1168014
 A7=109.56782545
 A8=121.41526041
 A9=119.43250855
 A10=119.16149663
 A11=120.39514569
 A12=127.07239212
 A13=129.93366075
 A14=125.22597923
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=0.
 D7=180.
 D8=180.
 D9=180.
 D10=180.
 D11=0.
 D12=180.
 D13=180.
  B1=1.41824763
 B2=1.39359982
 B3=1.38411621
 B4=1.40484597
 B5=1.40141521
 B6=1.43176428
 B7=1.36577109
 B8=1.37604915
 B9=1.08527225
 B10=1.08477387
 B11=1.08484238
 B12=1.08526903
 B13=1.07951825
 B14=1.07975346
 B15=1.00489735
 A1=122.42263917
 A2=117.39971915
 A3=121.23721842
 A4=118.69662272
 A5=134.43954194
 A6=107.0268607
 A7=109.58443003
 A8=121.514866
 A9=119.36763374
 A10=119.17025555
 A11=120.43319988
 A12=127.16759773
 A13=130.10817606
 A14=125.27146461
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=0.
 D7=180.
 D8=180.
 D9=180.
 D10=180.
 D11=0.
 D12=180.
 D13=180.





 














Table 4.  Indole.  Rotational Constants (MHz) and Dipole Moments * (D).







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

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








ropt(1) ropt(2)       Expt [2]







A
 3907.9
 3905.6
 3877.839600(88)

B
 1643.0
 1645.3
 1636.046217(35)

C
 1156.7
 1157.6
 1150.900598(26)







|µa| 1.51
 1.52


|µb| 1.54
 1.56


 




* B3PW91/6-311+G(df,pd) dipole moment calculation on ropt structures.













 













Table 5.  Indole.  B3LYP/cc-pVTZ Quartic Centrifugal Distortion Constants (Hz).







  Calc
 Expt [2]






Delta_J
   33.8
   35.05(42)

Delta_JK   50.0
   47.7(24)

Delta_K 273.
 271.(14)

delta_j   10.3
   10.18(19)

delta_k   89.3
   94.9(63)



 








 








[1] R.D.Suenram, F.J.Lovas, and G.T.Fraser, J.Mol.Spectrosc. 127,472(1988).

[2] R.Nesvadba, T.Studecký, T.Uhlíková, and Š.Urban, J.Mol.Spectros. 339,6(2017).

 








 








Pyrrole
Pyrazole
 Imidazole
 Carbazole

 








 








Table of Contents




Molecules/Nitrogen




 








 













Indole.html






Last Modified 26 June 2017