CH3-NH-CH2CH2NH2

























 









Nitrogen


Nuclear Quadrupole Coupling Constants


in  N-Methyl Ethylenediamine


 








 








Calculation was made of the 14N nqcc tensor in N-methyl ethylenediamine (MED) - T2t and T1 conformers - on ropt structures given by MP2/6-311++G(d,p) and MP2/6-311+G(3df,3pd) optimization.  These calculated nqcc's are compared with the (limited) experimental values of Caminati et al. [1] in Tables 1 - 4.  Structure parameters are given in Tabe 5, rotational constants and dipole moments in Table 6, quartic centrifugal distortion constants for T2t in Table 7.











T2t-MED

T1-MED























At the MP2/6-311+G(3df,3pd) level of theory, ET1 < ET2t by 1.35 kJ/mol.  A third conformer - designated T2g - was assigned by Caminati et al. [2] and is 2.72(63) kJ/mol higher in energy than T1 [2].











In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor.  Subscripts x,y,z refer to the principal axes of the nqcc tensor.  ETA = (Xxx - Xyy)/Xzz.  RSD is the residual standard deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the efg's/nqcc's.  

 








 








   







Table 1.  14N (C-NH-C) nqcc's in T2t-MED (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) MP2/6-311+G(3df,3pd) ropt structures.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa
1.642
1.679



Xbb - Xcc -
 5.891
 -
 5.799
 -
 5.52(15)

Xbb -
 3.766
 -
 3.739



Xcc
2.125
2.060



Xab
2.749
2.677



Xac
0.463
0.534



Xbc -
 1.037
 -
 1.242



 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
2.302
2.314



Xyy
2.795
2.779



Xzz -
 5.097
 -
 5.094



ETA
0.0968
0.0912



 








 








 








   







Table 2.  14N (C-NH2) nqcc's in T2t-MED (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) MP2/6-311+G(3df,3pd) ropt structures.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa
2.009
2.000



Xbb - Xcc
7.186
7.155
6.79(14)

Xbb
2.588
2.577



Xcc -
 4.597
 -
 4.577



Xab -
 0.408
 -
 0.418



Xac
0.507
0.529



Xbc
0.254
0.322



 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.848
1.840



Xyy
2.799
2.797



Xzz -
 4.647
 -
 4.637



ETA
0.205
0.206



 








 


















   







Table 3.  14N (C-NH-C) nqcc's in T1-MED (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) MP2/6-311+G(3df,3pd) ropt structures.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa
2.809
2.798



Xbb - Xcc
5.751
5.754
6.04(16)

Xbb
1.471
1.478



Xcc -
 4.280
 -
 4.276



Xab -
 0.549
 -
 0.541



Xac
0.556
0.551



Xbc
2.124
2.112



 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
2.029
2.029



Xyy
3.014
3.000



Xzz -
 5.042
 -
 5.029



ETA
0.195
0.193



 




























   







Table 4.  14N (C-NH2) nqcc's in T1-MED (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) MP2/6-311+G(3df,3pd) ropt structures.
   









Calc. (1)
Calc. (2)
Expt. [1]
   







Xaa -
 1.135
 -
 1.073



Xbb - Xcc -
 2.209
 -
 2.154
 -
 1.68(17)

Xbb -
 0.537 -
 0.540



Xcc
1.672
1.614



Xab
3.378
3.344



Xac
1.051
1.119



Xbc -
 1.307
 -
 1.389



 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.998
1.995



Xyy
2.664
2.663



Xzz -
 4.662
 -
 4.658



ETA
0.143
0.143



 

















 
 



Table 5.  C(1)H3-N(2)H-C(3)H2C(4)H2N(5)H2  Heavy atom structure parameters (1) MP2/6-311++G(d,p) and (2) MP2/6-311+G(3df,3pd) (Å and degrees).  Complete structures are given here in Z-matrix format.
 




_________T2t__________
 _________T1__________

ropt (1)
 ropt (2)ropt (1) ropt (2)





C(1)N(2) 1.4608
 1.4559
1.4572
 1.4526
N(2)C(3) 1.4624
 1.4577
1.4537
 1.4498
C(3)C(4) 1.5213
 1.5158
1.5222
 1.5166
C(4)N(5) 1.4623
 1.4584
1.4696
 1.4653
C(1)N(2)C(3) 112.34
 112.15
112.49
 112.33
N(2)C(3)C(4) 110.03
 109.99
110.00
 110.06
C(3)C(4)N(5) 109.10
 109.07
109.30
 109.23
C(1)N(2)C(3)C(4) - 173.24
 -174.84
 -170.53
 -170.60
N(2)C(3)C(4)N(5) 64.68
 64.72
 63.13
 62.94



 























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







__________________T2t___________________


ropt (1) ropt (1) Expt [1]






A
 12106
 12273
 12191.072(7)

B
   2585
   2597
   2560.444(3)

C
   2361
   2373
   2340.702(2)

|µa|
   0.64
   0.63

|µb|   0.89
   0.86

|µc|   1.59
   1.62







__________________T1____________________

A
 12046
 12128

B
   2594
   2613

C
   2358
   2375

|µa|   1.35
   1.34

|µb|   0.36
   0.36

|µc|   1.22
   1.25






























Table 7.  Quartic Centrifugal Distortion Constants (kHz).  Calc = B3lyp/cc-pVTZ











___________T2t____________




Calc
Expt [1]









Delta_J
0.969
0.96(1)


Delta_JK -
 8.04
 -
 8.35(9)


Delta_K
74.9
75.7(1)


delta_J
0.179
0.180(2)


delta_K
1.91
0.8(6)



















 








[1] W.Caminati, P.G.Favero, A.Millemaggi, L.B.Favero, and S.Melandri, J.Mol.Spectrosc. 171,385(1995).

[2] W.Caminati, A.C.Fantoni, and B.Velino, J.Mol.Struct. 157,385(1987).



















Dimethylamine
 Diethylamine
 Ethylamine
 Methylamine

 


















Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 9 March 2014