C2H3N3











 



























Nitrogen


Nuclear Quadrupole Coupling Constants


in 1H-1,2,3-Triazole


 








 








 








Analysis of the hyperfine structure in the microwave spectrum of 1H-1,2,3-triazole was undertaken by Blackman et al. [1].  Quadrupole coupling constants for each of the three inequivalent 14N nuclei have been obtained.

 








Calculation of the 14N nqcc tensors was made here on molecular structures given by MP2/cc-pVTZ and B3LYP/cc-pVTZ optimization.  These nqcc's are given compared with the experimental values in Tables 1 - 3.  Structure parameters are given in Table 4, rotational constants and dipole moments in Table 5.

 








In Tables 1 - 3, 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, and Ø (degrees) is the angle between its subscripted parameters.

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(1) nqcc's in 1H-1,2,3-Triazole (MHz).  Calculation was made on molecular structures given by (1) MP2/cc-pVTZ and (2) B3LYP/cc-pVTZ optimization.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa
1.545
1.754
0.64(28)

Xbb
0.914
0.834
3.22(44)

Xcc -
 2.459
 -
 2.587
 -
 3.86

|Xab|
0.507
0.393
1.04

 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
0.632
0.688
0.27

Xyy
1.827
1.899
3.58

Xzz -
 2.459
 -
 2.587
 -
 3.86

ETA
0.486
0.468
0.858

Øz,c
  0 *
  0 *



 








 








* z-principal axis lies along c-axis, which is perpendicular to the molecular plane.

 








 








   







Table 2.  14N(2) nqcc's in 1H-1,2,3-Triazole (MHz).  Calculation was made on molecular structures given by (1) MP2/cc-pVTZ and (2) B3LYP/cc-pVTZ optimization.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa
3.665
3.321
3.62(14)

Xbb -
 4.223
 -
 4.039
 -
 4.15(17)

Xcc
0.558
0.718
0.53

|Xab|
0.485
1.708
1.17

 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
0.558
0.718
0.53

Xyy
3.695
3.698
3.79

Xzz -
 4.253
 -
 4.416
 -
 4.33

ETA
0.737
0.675
0.752

Øz,a
86.49
77.55



Øa,bi *







Øz,bi







 








 








* "bi" is the external bisector of the N(1)N(2)N(3) angle.

 








 








   







Table 3.  14N(3) nqcc's in 1H-1,2,3-Triazole (MHz).  Calculation was made on molecular structures given by (1) MP2/cc-pVTZ and (2) B3LYP/cc-pVTZ optimization.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa -
 4.224
 -
 4.758
 -
 4.77(14)

Xbb
2.023
2.440
2.57(14)

Xcc
2.201
2.318
2.29

|Xab|
1.985
0.727
0.90

 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
2.201
2.318
2.19

Xyy
2.601
2.513
2.68

Xzz -
 4.802
 -
 4.831
 -
 4.87

ETA
0.0833
0.0404
0.101

Øz,a
16.22
  5.71



Øa,bi *







Øz,bi







 








 








* "bi" is the external bisector of the N(2)N(3)C(4) angle.




















 
 

Table 4.  1H-1,2,3-Triazole.  Molecular structure parameters, ropt (Å and degrees).
 



 N
 N,1,B1
 N,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 C,1,B4,2,A3,3,D2,0
 H,5,B5,1,A4,2,D3,0
 H,1,B6,5,A5,4,D4,0
 H,4,B7,3,A6,2,D5,0


 MP2/cc-pVTZ B3LYP/cc-pVTZ


 B1=1.34293129
 B2=1.32268873
 B3=1.35686646
 B4=1.3511174
 B5=1.07381824
 B6=1.00698161
 B7=1.07440306
 A1=106.50316381
 A2=108.71280494
 A3=112.28565402
 A4=123.1752898
 A5=128.88892082
 A6=121.65769432
 D1=0.
 D2=0.
 D3=180.
 D4=180.
 D5=180.
  B1=1.344898
 B2=1.29759399
 B3=1.36132003
 B4=1.35167888
 B5=1.07478441
 B6=1.00599812
 B7=1.07498517
 A1=106.98714697
 A2=109.25692548
 A3=111.48579997
 A4=123.21170395
 A5=129.12876498
 A6=121.83234604
 D1=0.
 D2=0.
 D3=180.
 D4=180.
 D5=180.






 








 














Table 5.  1H-1,2,3-Triazole.  Rotational Constants (MHz) and Dipole Moments * (D).







MP2/cc-pVTZ and B3LYP/cc-pVTZ optimization








  MP2 B3LYP Expt [1]







 A
 10332.8
 10308.2
 10030.71

 B
   9822.1
   9922.4
   9870.56

 C
   5035.5
   5055.8
   4972.96







|µa|   1.06
   0.85


|µb|   2.76
   2.80








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













 








[1] G.L.Blackman, R.D.Brown, F.R.Burden, and W.Garland, J.Mol.Spectrosc. 65,313(1977).

 








 








1,2,4-Triazole
Imidazole Pyrazole Pyrrole

 








 








Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 18 Aug 2015