CH2CH3N(H)C(=O)H

























 








Nitrogen


Nuclear Quadrupole Coupling Constants


in N-Ethylformamide trans-synclinal



 








 








 








Nitrogen nqcc's in N-ethylformamide, and a heavy atom substitution structure were determined by Ohba et al. [1].  Calculation of the nqcc's was made here on this structure complemented by MP2/6-311+G(d,p) optimization for the hydrogen structure, and on a structure given by HF/aug-cc-pVTZ optimization.  Calculated and experimental nqcc's are compared in Table 1.  Structure parameters are given in Table 2, rs/ropt atomic coordinates in Table 3, rotational constants in Table 4.


 








In Table 1, 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.  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 the nitrogen efg's/nqcc's.

 








 








 








Table 1. 14N nqcc's in N-Ethylformamide (MHz).  Calculation was made on the rs/ropt structure (the derivation of which is briefly discussed below), and on an ropt structure given by HF/aug-cc-pVTZ optimization.
 










Calc rs/ropt
Calc ropt
Expt. [1]
 








Xaa
1.389
1.384

1.3794(13)

Xbb
0.845
0.795

0.8171(20)

Xcc - 2.234 -
2.179
- 2.1965(20)

Xab
- 0.735 -
0.592




Xac
- 1.536 -
1.569




Xbc
- 2.318 -
2.265













RMS
0.027 (1.9 %)
0.017 (1.1 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)












Xxx
1.896
1.740




Xyy
2.117
2.183




Xzz - 4.013 -
3.923




ETA
0.055
0.113














 








 








 

Table 2.  Molecular structure parameters, rs/ropt and ropt = HF/aug-cc-pVTZ optimization. (Å and degrees).  The rs/ropt structure was derived with substitution parameters were held fixed, while hydrogen atom parameters were determined by partial optimization at the MP2/6-311+G(d,p) level of theory.






 C
 O,1,B1
 N,1,B2,2,A1
 C,3,B3,1,A2,2,D1,0
 C,4,B4,3,A3,1,D2,0
 H,3,B5,1,A4,2,D3,0
 H,1,B6,2,A5,3,D4,0
 H,4,B7,3,A6,1,D5,0
 H,4,B8,3,A7,1,D6,0
 H,5,B9,4,A8,3,D7,0
 H,5,B10,4,A9,3,D8,0
 H,5,B11,4,A10,3,D9,0


   rs/ropt    ropt


 B1=1.2173
 B2=1.3757
 B3=1.439
 B4=1.5155
 B5=1.00888616
 B6=1.10448059
 B7=1.09430186
 B8=1.09332725
 B9=1.0924911
 B10=1.09445652
 B11=1.09414336
 A1=124.02
 A2=121.27
 A3=113.2
 A4=117.88106556
 A5=123.4769532
 A6=107.84966238
 A7=107.38619512
 A8=110.08425781
 A9=110.50669638
 A10=110.83813921
 D1=-1.99
 D2=-82.17
 D3=-174.99295103
 D4=179.3530347
 D5=154.94222193
 D6=39.32471617
 D7=59.90859603
 D8=179.63296236
 D9=-60.29538215
 B1=1.19185096
 B2=1.34234003
 B3=1.45100172
 B4=1.52249681
 B5=0.99027358
 B6=1.09118643
 B7=1.08263965
 B8=1.07924826
 B9=1.08212832
 B10=1.08410104
 B11=1.08448513
 A1=125.42622743
 A2=123.29927667
 A3=113.32719559
 A4=117.45192601
 A5=121.85446325
 A6=107.63531568
 A7=107.58796065
 A8=110.55833374
 A9=110.16227437
 A10=111.10365887
 D1=-2.13060465
 D2=-87.7293937
 D3=-176.55919949
 D4=179.34834596
 D5=149.97218516
 D6=34.25154375
 D7=60.43270112
 D8=-179.83435772
 D9=-60.05872636





 








 
















Table 3.  N-Ethylformamide.  Atomic coordinates, rs/ropt.
 









  a (Å)
  b (Å)
  c (Å)









C
1.281521
0.280872 - 0.252688

O
1.511462 - 0.835396
0.174971

N
0.078050
0.930079 - 0.101902

C - 1.034828
0.297267
0.555192

C - 1.817173 - 0.628812 - 0.354234

H - 0.037555
1.821794 - 0.559429

H
2.024607
0.889378 - 0.798052

H - 1.680720
1.085157
0.954626

H - 0.636495 - 0.264133
1.404619

H - 1.167410 - 1.422596 - 0.730068

H - 2.646926 - 1.090075
0.190359

H - 2.228511 - 0.080670 - 1.207163


 








 













Table 4. N-Ethylformamide.  Rotational constants (MHz):  rs/ropt and ropt = HF/aug-cc-pVTZ.
 





 rs/ropt   ropt     Expt. [1]






A 9873.9 10590.3
9904.8373(6)

B 3555.3   3373.2
3521.0995(2)

C 3002.7   2935.8
2984.9808(2)


 








 








[1] K.Ohba, T.Usami, Y.Kawashima, and E.Hirota, J.Mol.Struct. 744-747,815(2005).

 








V.Vaquero-Vara, V.Alstadt, T.P.Sewatsky, J.L.Claughton, I.A.Finneran, S.T.Shipman, B.H.Pate, and D.W.Pratt, J.Mol.Spectros. 335,102(2017): Xaa = 1.379(2), Xbb = 0.816(13), Xcc = -2.195(13) MHz


 









 









Formamide Acetamide Dimethylamine


N-Methylacetamide N-Ethylformamide cis-ac




 








 








Table of Contents




Molecules/Nitrogen




 








 













NEFA.html






Last Modified 6 July 2017