CH2·NH·CH(CH3)





 


















 










Nitrogen


Nuclear Quadrupole Coupling Constants

in 2-Methylaziridine (Propyleneimine)


 








 








The microwave spectra of cis-2-methylaziridine was observed and assigned by Li and Durig [1], and by Schmidt and Beeson [2]. 14N  nuclear quadrupole coupling constants were determined.

 









Here, for both cis and trans conformers - shown below, calculation of the nitrogen nqcc tensor was made on molecular structures given by MP2/6-311+G(d,p) and MP2/6-311+G(3df,3pd) optimization.  These calculated nqcc's are compaed with experimental values [1] in Tables 1 and 2.  Structure parameters are given in Z-Matrix format in Table 3, rotational constants and dipole moments in Table 4, quartic centrifugal distortion constants in Table 5.


 








cis-2-Methylaziridine

trans-2-Methylaziridine


At the



MP2/6-311+G(3df,3pd)

level of theory,


Etrans < Ecis


by 2.1 kJ/mol
















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.  ETA = (Xxx - Xyy)/Xzz.  Ø (degrees) is the angle between its subscripted parameters.


RMS is the root mean square difference between calculated and experimental nqcc's.  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen efg's/nqcc's.

 









 








 
   








Table 1.  14N nqcc tensor in cis-2-Methylaziridine (MHz).  Calculation was made on  molecular structures given by (1) MP2/6-311+G(d,p) and (2) MP2/6-311+G(3df,3pd)  optimization.
   










Calc (1)
Calc (2)

Expt [1]

   








Xaa -
1.167
-
1.192
-
1.16(2)


Xbb
1.778

1.800

1.80(2)


Xcc -
0.611
-
0.608
-
0.64(2)


Xab

0.676

0.698




Xac
1.999

1.999




Xbc -
2.106
-
2.115




 








RMS

0.021 (1.8 %)

0.026 (2.2 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
0.551

0.552




Xyy
3.058

3.077




Xzz -
3.609

3.629




ETA
0.694

0.696




Øz,NH
132.1

131.8














 









 








   








Table 2.  14N nqcc tensor in trans-2-Methylaziridine (MHz).  Calculation was made on  molecular structures given by (1) MP2/6-311+G(d,p) and (2) MP2/6-311+G(3df,3pd)  optimization.
   










Calc (1)
Calc (2)

Expt

   








Xaa
0.813

0.798




Xbb
2.063

2.071




Xcc -
2.876
-
2.869




Xab
-
1.391
-
1.406




Xac -
0.944
-
0.963




Xbc -
1.244
-
1.243




 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
0.526

0.519




Xyy
3.018

3.031




Xzz -
3.543
-
3.550




ETA
0.703

0.707




Øz,NH
132.4

132.3














 








 









 









Table 3.  2-Methylaziridine:  MP2/6-311+G(d,p) and MP2/6-311+G(3df,3pd) optimized structure parameters (Å and degrees).










cis-2-Methylaziridine
trans-2-Methylaziridine

           N
           C,1,B1
           C,1,B2,2,A1
           H,1,B3,2,A2,3,D1,0
           H,3,B4,1,A3,2,D2,0
           H,2,B5,1,A4,3,D3,0
           H,2,B6,1,A5,3,D4,0
           C,3,B7,1,A6,2,D5,0
           H,8,B8,3,A7,1,D6,0
           H,8,B9,3,A8,1,D7,0
           H,8,B10,3,A9,1,D8,0





____________________ MP2/6-311+G(d,p)____________________

    cis



   trans



 B1=1.48455468
 B2=1.47718299
 B3=1.01960358
 B4=1.0869794
 B5=1.08404927
 B6=1.08672656
 B7=1.50764998
 B8=1.09465623
 B9=1.09467929
 B10=1.09562601
 A1=60.10403013
 A2=108.43032232
 A3=112.34906577
 A4=114.49349698
 A5=118.02587932
 A6=119.84653164
 A7=110.94814244
 A8=110.88386996
 A9=110.29693244
 D1=101.04559283
 D2=-109.62506439
 D3=112.1129528
 D4=-106.65790104
 D5=109.84068261
 D6=77.21044473
 D7=-162.43218221
 D8=-42.82151946

 B1=1.4833335
 B2=1.47743414
 B3=1.01805204
 B4=1.08877059
 B5=1.08582525
 B6=1.08496902
 B7=1.50522401
 B8=1.0944112
 B9=1.0947942
 B10=1.09321847
 A1=60.18368895
 A2=108.93428396
 A3=116.28779387
 A4=118.24642232
 A5=114.20776719
 A6=115.78471968
 A7=110.73809611
 A8=110.84591935
 A9=109.5315166
 D1=-102.23126317
 D2=-105.94736
 D3=108.08212475
 D4=-110.7183989
 D5=112.85626432
 D6=81.42600796
 D7=-157.95978902
 D8=-37.83352299










____________________ MP2/6-311+G(3df,3pd)____________________

   cis



   trans



 B1=1.47903111
 B2=1.47057676
 B3=1.01571814
 B4=1.08280119
 B5=1.07978458
 B6=1.0819464
 B7=1.50131819
 B8=1.0898696
 B9=1.0897449
 B10=1.09076623
 A1=60.09632531
 A2=108.67131248
 A3=112.33603282
 A4=114.30819877
 A5=117.87752209
 A6=119.47904473
 A7=110.96781997
 A8=110.998557
 A9=110.34458921
 D1=101.08504192
 D2=-109.60061196
 D3=112.20234954
 D4=-106.71903851
 D5=109.96800372
 D6=76.89032242
 D7=-162.87302226
 D8=-43.11520196

 B1=1.47784688
 B2=1.47215681
 B3=1.01424742
 B4=1.08387826
 B5=1.08094524
 B6=1.08065069
 B7=1.4996737
 B8=1.08918986
 B9=1.08974834
 B10=1.08840126
 A1=60.11424879
 A2=109.07451674
 A3=116.32943696
 A4=118.17126295
 A5=114.06672114
 A6=115.47405408
 A7=110.76970213
 A8=110.94088848
 A9=109.63441925
 D1=-102.37611586
 D2=-106.06808881
 D3=108.31965798
 D4=-110.63752867
 D5=112.79938152
 D6=81.33047717
 D7=-158.08515319
 D8=-37.89761827























 





Table 4.  2-Methylaziridine:  Rotational Constants (MHz) and Dipole Moments (D).  Calc (1)  =  MP2/6-311+G(d,p) and Calc (2) = MP2/6-311+G(3df,3pd) optimization.








__________cis-2-Methylaziridine__________



Calc (1)
Calc (2)
 Expt [1]







A 16689
16813


B   6561
  6624


C   5818
  5875


a|
  1.41
  1.40



b|   1.10
  1.10



c|   0.87
  0.87










__________trans-2-Methylaziridine__________


Calc (1)
Calc (2)
 Expt [1]








A
16928
17044



B
  6535
  6596



C
  5765
  5821



a|   0.11
  0.12



b|   0.88
  0.88



c|   1.54
  1.54




 








 















Table 5.  2-Methylaziridine:  Quartic Centrifugal Distortion Constants (kHz).  Calc = B3LYP/cc-pVTZ









____cis-2-Methylaziridine____
___trans-2-Methylaziridine___


Calc
Expt

Calc
Expt







Delta_J

2.73


2.72

Delta_JK
4.21


3.21

Delta_K
12.8


15.5

delta_J
0.188


0.241

delta_K
3.25


3.48








D_J
2.68


2.66

D_JK
4.55


3.57

D_K
12.5


15.2

d_1
-
0.188

-
0.241

d_2
-
0.0281

-
00303










 








 








[1] Y.S.Li and J.R.Durig, J. Mol. Spectrosc. 47,179(1973).


[2] R.Schmidt and E.L.Beeson Jr., J.Chem.Phys. 59,3070(1973):  Xaa, Xbb, Xcc = -1.14(6), 2.01(5), -0.88(7) MHz.












 









Aziridine
2-Cyanoaziridine
1-Aziridineethanol























Table of Contents




Molecules/Nitrogen




 








 













2MeAziridine.html






Last Modified 30 Jan 2014