Indazole

































 
















Nitrogen


Nuclear Quadrupole Coupling Constants


in Indazole


 








 








 


 





The microwave spectrum of indazole was investigated by Velino et al. [1].  The tautomer with the NH group closer to the phenyl ring was found to be the more stable of two possibilities.


 








Calculation of the 14N nqcc tensors in indazole was made here on a molecular structure of this more stable tautomer given by B3LYP/cc-pVTZ optimization.  These calculated nqcc's are compared with experimental values [2]  in Tables 1 and 2, structure parameters in Z-matrix format in Table 3.  Rotational constants, dipole moments, and quartic centrifugal distortion constants are given in Table 4.


 








In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

RMS is the root mean square difference between calculated and experimental nqcc's (percentage of the average of the magnitudes of the experimental 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.  Nitrogen (Pyrrolic) nqcc's in Indazole (MHz).  Calculation was made on B3LYP/cc-pVTZ ropt structure.

   










Calc.
Expt. [2]

   







14N Xaa
1.973

1.9688(52)



Xbb
1.951

1.9310(48)



Xcc -
3.925

3.8998(48)



|Xab|
0.783




 







RMS

0.019 (0.7 %)





RSD
0.030 (1.3 %)



 







Xxx
1.179




Xyy
2.746



  Xzz - 3.925



  ETA
0.399




z,c
0.



 







 








 








   







Table 2.  Nitrogen (Pyridinic) nqcc's in Indazole (MHz).  Calculation was made on B3LYP/cc-pVTZ ropt structure.

   










Calc
Expt [2]

   







14N Xaa - 4.078 -
4.0462(41)



Xbb
2.655
2.6841(47)



Xcc
1.423
1.3621(47)



|Xab|
2.509



 







RMS

0.043 (1.6 %)





RSD
0.030 (1.3 %)



 







Xxx
3.488




Xyy
1.423



  Xzz - 4.911



  ETA - 0.420




z,a
18.35




a,bi
  0.97





z,bi *
17.38



 







 








* Angle between the z-axis and the bisector ( 'bi' ) of the NNC angle.

 







 
 


Table 3.  Indazole.  Molecular structure parameters, ropt ( and degrees).
 



 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
 N,1,B6,6,A5,5,D4,0
 N,7,B7,1,A6,6,D5,0
 C,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,9,B14,8,A13,7,D12,0





 B1=1.41373741
 B2=1.40204864
 B3=1.37948082
 B4=1.40985914
 B5=1.39875971
 B6=1.36344288
 B7=1.35483135
 B8=1.31560925
 B9=1.08191983
 B10=1.08143881
 B11=1.08183938
 B12=1.08156911
 B13=1.00340846
 B14=1.07770255
 A1=119.51574294
 A2=118.5128222
 A3=121.12285528
 A4=122.12709066
 A5=132.22702673
 A6=112.53191763
 A7=106.0659651
 A8=120.73592207
 A9=119.82950285
 A10=119.03431939
 A11=121.74007109
 A12=128.5277164
 A13=119.80171637

 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=0.
 D7=180.
 D8=180.
 D9=180.
 D10=180.
 D11=0.
 D12=180.








 








 




Table 4.  Indazole.  Rotational Constants (MHz), Dipole Moments (D), and Quartic Centrifugal Distortion Constants (kHz).  Calc = B3LYP/cc-pVTZ






 

Calc

     Expt [2]







A

4010.

3977.93108(45)

B

1641.

1633.27746(22)

C

1164.

1158.13382(21)







|a|

1.25



|b|
1.13









Delta_J

0.0347

0.0255(36)

Delta_JK
0.0461

0.0419(87)

Delta_K
0.301

0.323(46)

delta_J
0.0105



delta_K
0.0913










 









 








[1] B.Velino, E.Can, and A.Trombetti, J.Mol.Spectrosc. 155,1(1992).


[2] I.Uriarte, F.Reviriego, C.Calabrese, J.Elguero, Z.Kisiel, I.Alkorta, and E.J.Cocinero, Chem. Euro. J. 25(43),10172(2019).


 








 








Pyrazole
Imidazole Pyrrole


Carbazole
Indole





 








 








Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 15 June 2019