CH3CH=N-CH3















 









Nitrogen


Nuclear Quadrupole Coupling Constants

in N-Methylethylidenimine


 


















The microwave spectrum of N-methylethylidenimine was observed and assigned by Meier et al. [1].






















Conformer A


Conformer B







EA  <  EB


by 8.4 kJ/mol


at MP2/6-311+G(3d,3p)


level of theory


















Calculation of the nitrogen nqcc tensor in each conformer shown above was made on ropt molecular structures given by MP2/6-311+G(3d,3p) and B3P86/6-311+G(3d,3p) optimization.  These are compared with the experimental nqcc's [1] in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants 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.  ETA = (Xxx - Xyy)/Xzz.  (degrees) is the angle between its subscripted parameters.


RMS is the root mean square difference between calculated and experimental diagonal 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.  14N nqcc's in N-Methylethylidenimine, conformers A and B (MHz).  Calculation was made on MP2/6-311+G(3d,3p) optimized structure.
 










Calc /A

Calc /B

Expt. [1]
 








Xaa
1.503

1.580

1.578(39)


Xbb
-
4.564
-
4.521
-
4.601(37)


Xcc
3.061

2.941

3.023(41)


Xab
0.101

0.086













RMS
0.053 (1.7 %)

0.066 (2.2 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)












Xxx
1.505

1.582




Xyy
3.061
2.941




Xzz -
4.566
-
4.522




ETA
0.341

0.300




z,a
89.0

89.2




a,N-C







z,N-C

















 









 








 








Table 2.  14N nqcc's in N-Methylethylidenimine, conformers A and B (MHz).  Calculation was made on B3P86/6-311+G(3d,3p) optimized structure.
 










Calc /A

Calc /B

Expt. [1]
 








Xaa
1.511

1.600

1.578(39)

Xbb
-
4.638
-
4.614
-
4.601(37)

Xcc
3.127

3.014

3.023(41)

Xab
0.092

0.097













RMS
0.075 (2.4 %)

0.016 (0.52 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)












Xxx
1.512

1.602




Xyy
3.127

3.014




Xzz -
4.639
-
4.616




ETA
0.348

0.306




z,a
89.1

89.1




a,N-C







z,N-C

















 









 









 




Table 3.  N-Methylethylidenimine.  MP2/6-311+G(3d,3p) and B3P86/6-311+G(3d,3p) optimized structure parameters ( and degrees).






Conformer A






 H
 C,1,B1
 N,2,B2,1,A1
 C,2,B3,1,A2,3,D1,0
 H,4,B4,2,A3,1,D2,0
 H,4,B5,2,A4,1,D3,0
 H,4,B6,2,A5,1,D4,0
 C,3,B7,2,A6,1,D5,0
 H,8,B8,3,A7,2,D6,0
 H,8,B9,3,A8,2,D7,0
 H,8,B10,3,A9,2,D8,0








MP2
B3P86








 B1=1.09867503
 B2=1.27557858
 B3=1.49558173
 B4=1.09036791
 B5=1.08612884
 B6=1.09036791
 B7=1.4550771
 B8=1.0957449
 B9=1.08857036
 B10=1.08857036
 A1=120.95422774
 A2=117.09376571
 A3=110.27644428
 A4=110.09595125
 A5=110.27644428
 A6=116.81659861
 A7=113.13375191
 A8=108.93363333
 A9=108.93363333
 D1=180.
 D2=59.08482646
 D3=180.
 D4=-59.08482646
 D5=0.
 D6=0.
 D7=121.53477697
 D8=-121.53477697
 B1=1.10150248
 B2=1.26176601
 B3=1.48976364
 B4=1.09277791
 B5=1.08761052
 B6=1.09277791
 B7=1.44229573
 B8=1.09837409
 B9=1.09163771
 B10=1.09163771
 A1=120.94307496
 A2=116.52979244
 A3=110.41099341
 A4=110.47398196
 A5=110.41099341
 A6=118.03257793
 A7=113.62517162
 A8=109.23698563
 A9=109.23698563
 D1=180.
 D2=58.86887781
 D3=180.
 D4=-58.86887781
 D5=0.
 D6=0.
 D7=121.7916195
 D8=-121.7916195

















Conformer B








 H
 C,1,B1
 N,2,B2,1,A1
 C,2,B3,1,A2,3,D1,0
 H,4,B4,2,A3,1,D2,0
 H,4,B5,2,A4,1,D3,0
 H,4,B6,2,A5,1,D4,0
 C,3,B7,2,A6,1,D5,0
 H,8,B8,3,A7,2,D6,0
 H,8,B9,3,A8,2,D7,0
 H,8,B10,3,A9,2,D8,0







MP2
B3P86








 B1=1.09907705
 B2=1.27586595
 B3=1.49541325
 B4=1.09048763
 B5=1.08624325
 B6=1.09048763
 B7=1.46646725
 B8=1.08558134
 B9=1.09081467
 B10=1.09081467
 A1=121.30874769
 A2=116.87035206
 A3=110.31483284
 A4=109.97701774
 A5=110.31483284
 A6=115.92870607
 A7=109.32536233
 A8=110.97056506
 A9=110.97056506
 D1=180.
 D2=59.09141852
 D3=180.
 D4=-59.09141852
 D5=0.
 D6=180.
 D7=-60.43335687
 D8=60.43335687
 B1=1.10166169
 B2=1.26184885
 B3=1.48976139
 B4=1.09293753
 B5=1.08769053
 B6=1.09293753
 B7=1.45380203
 B8=1.08829268
 B9=1.09350611
 B10=1.09350611
 A1=121.52781913
 A2=116.19566673
 A3=110.44116355
 A4=110.37203058
 A5=110.44116355
 A6=117.52333047
 A7=109.59993527
 A8=111.50658882
 A9=111.50658882
 D1=180.
 D2=58.86407226
 D3=180.
 D4=-58.86407226
 D5=0.
 D6=180.
 D7=-60.46596605
 D8=60.46596605








 














Table 4.  N-Methylethylidenimine.  Rotational Constants (MHz).  Calculation was made on the  MP2/6-311+G(3d,3p) and B3P86/6-311+G(3d,3p) optimized structures.








Calc /MP2
Calc /B3P86
    Expt [1]







Conf. A
A
  38390.
  39041.
38258.627(48)


B
    4089.
    4110.
  4078.1354(58)


C
    3871.
    3896.
  3862.7391(72)







Conf. B A
  38135.
  38858.
38258.627(48)

B
    4088.
    4103.
  4078.1354(58)

C
    3869.
    3889.
  3862.7391(72)



 








 









[1] J.Meier, A.Bauder, and Hs.H.Gnthard, J.Chem.Phys. 57,1219(1972).


 








 








N-Methylmethanimine





 








 








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Molecules/Nitrogen




 








 













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Last Modified 20 Oct 2016