CH3-NH-CH2CH2OH















 








 









Nitrogen


Nuclear Quadrupole Coupling Constants

in 2-Methylaminoethanol


 








 








 


 





14N nqcc's in 2-methylaminoethanol were determined by Calabrese et al. [1], electric dipole moments by Penn and Buxton [2].


Calculation of the 14N nuclear quadrupole coupling constant tensors, as well as the dipole miments, in each of the following conformers of the title molecule was made here on ropt molecular structures given by MP2/6-311++G(d,p) and MP2/6-311+G(df,pd) optimization.


 








Conformer gG'T


Conformer g'GG
























EgG'T < Eg'GG by 0.15 kJ/mole at MP2/6-311+G(df,pd) level of theory.

 









Calculated and experimental nitrogen nqcc's are compared in Tables 1 and 2, rotational constants and electric dipole moments in Table 3.  Optimized structure parameters are given here in Z-Matrix format.


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)/Xzzz,NH  is angle between the z-principal axes of the nqcc tensor and the NH bond axis.  RMS is the root mean square difference between calculated and experiment diagonal nqcc's (percent of average magnitude of experimental nqcc's).  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the efg's/nqcc's. 


 








 








   








Table 1.  14N nqcc's in 2-Methylaminoethanol, conformer gG'T (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) MP2/6-311+G(df,pd) ropt structures.

   










Calc (1)
Calc (2)

Expt [1]

   








Xaa
1.455

1.425

1.578(2)


Xbb -
3.488
-
3.468
-
3.420(4) *


Xcc
2.033

2.043

1.842(4) *


Xab -
2.859
-
2.871




Xac -
0.509
-
0.524




Xbc -
1.069
-
1.087




 







RMS

0.137 (6.0 %)

0.149 (6.5 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)



 








Xxx
2.764
2.751




Xyy
2.231

2.249




Xzz -
4.995
-
5.000




ETA
-
0.107
-
0.100




z,NH

110.9

110.6














 








* Calculated here from Xaa and Xbb - Xcc = -5.262(3) MHz


 









 









   








Table 2.  14N nqcc's in 2-Methylaminoethanol, conformer g'GG (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) MP2/6-311+G(df,pd) ropt structures.

   










Calc (1)
Calc (2)

Expt [1]

   








Xaa
0.510

0.476

0.510(7)


Xbb -
2.276
-
2.178
-
2.16(1) *


Xcc
1.766

1.702

1.65(1) *


Xab
3.373

3.349




Xac
0.802

0.896




Xbc -
1.575
-
1.674




 







RMS

0.09 (6.6 %)

0.04 (2.6 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)



 








Xxx
2.833
2.816




Xyy
2.155

2.171




Xzz -
4.988
-
4.987




ETA
-
0.136
-
0.129




z,NH

109.6

109.2














 









* Calculated here from Xaa and Xbb - Xcc = -3.81(1) MHz

 









 








 





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

 




Conf gG'T
ropt(1) ropt(2)   Expt [1,2]

 




 A
11951
11973
12123.7430(6)

 B
  2691
  2722
  2653.8058(2)

 C
  2431
  2454
  2400.7362(2)

|a|   2.49
  2.50
  2.272(8)

|b|   1.53
  1.52
  1.336(20)

|c|   0.87
  0.86
  0.808(18)

|tot|   3.05
  3.05
  2.756(13)

 




Conf g'GG




 




 A
  9200
  9159
  9155.314(2)

 B
  3091
  3150
  3076.3199(5)

 C
  2891
  2932
  2868.6381(4)

|a|   2.83
  2.82
  2.610(11)

|b|   1.39
  1.43
  1.132(11)

|c|   0.17
  0.16
  0.331(34)

|tot|   3.16
  3.17
  2.864(11)

 




* Calculated by B3PW91/6-311+G(df,pd) method on MP2 ropt structures.



 








 









[1] C.Calabrese, A.Maris, L.Evangelisti, A.Piras, V.Parravicin, and S.Melandri, Frontiers in Chemistry|www.frontiersin.org, Volume 6, Article 25 (2018).


[2] R.E.Penn and L.W.Buxton, J.Mol.Spectrosc. 56,229(1975).


 









S.Melandri, A.Maris, and C.Calabrese, Abstract WF15, 68th International Symposium on Molecular Spectroscopy, 2013.

 









 









Dimethylamine Diethylamine
Methylaminoethane
2-Dimethylaminoethanol

 









 









Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 18 April 2018