CH2=CH-NH-C(=O)H
















 








 








Nitrogen


Nuclear Quadrupole Coupling Constants

in N-Vinylformamide

 








 








 








The microwave spectrum of N-vinylformamide was first investigated by M°llendal and Samdal [1], which authors observed and established the planarity of the trans and cis conformers shown below.  Subsequently, 14N nqcc's were determined by Kannengie▀er, et al. [2]. 


 








trans CH2=CH-NH-C(=O)H

cis CH2=CH-NH-C(=O)H









































At MP2/6-311++G(d,p) level of theory, Etrans < Ecis by 1.8 kJ/mol.


 









Calculation was made of the 14N nqcc tensor on ropt molecular structures derived by MP2/6-311++G(d,p) optimization [2].  These are compared with the experimental nqcc's in Tables 1 and 2.  Structure parameters are given in Table 3.











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.  

RSD are the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) and B3PW91/6-311+G(d,p) models for calculation of the efg's/nqcc's.

 








 








 








Table 1. 14N nqcc's in trans CH2=CH-NH-C(=O)H (MHz).  Calculation was made on the ropt structure with (1) B3PW91/6-311+G(df,pd) and (2) B3PW91/6-311+G(d,p) models.













Calc (1)

Calc (2)
Expt [2]

 








Xaa
1.622
1.714

1.70574(90)


Xbb
1.893
1.955

1.9358(11)


Xcc -
3.515 -
3.669
-
3.6416(11)


|Xab|
0.060
0.070




 








RMS

0.091 (3.7 %)

0.020 (0.82 %)




RSD
0.030 (1.3 %)
0.086 (3.8 %)













Xxx
1.610
1.695




Xyy
1.906
1.974




Xzz - 3.515 *
-
3.669 *




ETA
0.0842
0.0759














 








* The z-principal axis is perpendicular to the plane of symmetry of the molecule.

 









 









 








Table 2. 14N nqcc's in cis CH2=CH-NH-C(=O)H (MHz).  Calculation was made on the ropt structure with (1) B3PW91/6-311+G(df,pd) and (2) B3PW91/6-311+G(d,p) models.













Calc (1)

Calc (2)
Expt [2]

 








Xaa
1.752
1.847

1.8520(14)


Xbb
1.701
1.759

1.7876(20)


Xcc -
3.454 -
3.606
-
3.6396(20)


|Xab|
0.151
0.151




 








RMS

0.131 (5.4 %)

0.026 (1.1 %)




RSD
0.030 (1.3 %)
0.086 (3.8 %)













Xxx
1.573
1.645




Xyy
1.880
1.961




Xzz - 3.454 *
-
3.606 *




ETA
0.0890
0.0875














 








* The z-principal axis is perpendicular to the plane of symmetry of the molecule.

 







 
 



Table 3.  N-Vinylformamide.  MP2/6-311++G(d,p) ropt structure parameters.  (┼ and degrees).
 





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








       trans
       cis







 B1=1.3417365
 B2=1.39929396
 B3=1.3758359
 B4=1.21663171
 B5=1.08418612
 B6=1.08567916
 B7=1.08210411
 B8=1.1037552
 B9=1.01084055
 A1=123.91982201
 A2=123.22195749
 A3=124.96366679
 A4=122.81240583
 A5=122.21166317
 A6=119.61894852
 A7=111.7887673
 A8=119.04529762
 D1=180.
 D2=0.
 D3=180.
 D4=0.
 D5=180.
 D6=180.
 D7=0.
 B1=1.34219018
 B2=1.39561164
 B3=1.3740195
 B4=1.21619249
 B5=1.0865399
 B6=1.0850312
 B7=1.08188585
 B8=1.10427614
 B9=1.01350557
 A1=124.70892026
 A2=124.25365678
 A3=124.33190674
 A4=113.86274933
 A5=121.99072264
 A6=119.64380536
 A7=112.22720839
 A8=119.54266375
 D1=180.
 D2=180.
 D3=0.
 D4=0.
 D5=180.
 D6=0.
 D7=0.









 









[1] H.M°llendal and S.Samdal, J.Phys.Chem. A 116,12073(2012).

[2] R.Kannengie▀er, W.Stahl, H.V.L.Nguyen, and W.C.Bailey, J.Mol.Spectrosc. 317,50(2015).

 









 








Formamide N-Methylformamide
Uracil

N-Methyldiacetamide
2-Pyridone
Amides


 








 









Table of Contents





Molecules/Nitrogen




 








 













CH2CHNHCOH.html






Last Modified 10 Sept 2015