(CH3)C(=O)NH(CH2CH3)































 









Nitrogen


Nuclear Quadrupole Coupling Constants

in N-Ethylacetamide


 








 









Molecular conformation and 14N nuclear quadrupole coupling constants in N-ethylacetamide were determined by Kannengießer, et al. [1]. 


 


 





Calculation of the 14N nuclear quadrupole coupling constants was made here on ropt molecular structures given by MP2/6-311++G(d,p) and HF/6-311++G(3df,3pd) optimization.


 








Calculated and experimental [1] nqcc's are compared in Table 1.  Structure parameters are given in Table 2, rotational constants in Table 3.


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.  Ø (degrees) is the angle between its subscripted parameters.  RMS is the root mean square difference between calculated and experimental diagonal 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-Ethylacetamide (MHz).  Calculation was made on the  MP2/6-311++G(d,p) and HF/6-311++G(3df,3pd) ropt structures.

   










Calc /MP2
Calc /HF

Expt [1]

   








Xaa
1.720

1.782

1.7508(32)


Xbb
1.829

1.867

1.8333(45) *


Xcc -
3.549
-
3.649
-
3.5841(45) *


Xab
0.146
-
0.018

0.1686 **


Xac
1.396

1.406
-
1.651(71)


Xbc -
1.046
-
0.628

0.595(59)


 







RMS

0.027 (1.1 %)

0.046 (1.9 %)




RSD
0.030 (1.3 %)

0.030 (1.3 %)



 








Xxx
1.929

1.835

1.898(12) ***


Xyy
2.153

2.219

2.220(37)


Xzz -
4.082
-
4.054
-
4.118(39)


ETA

0.0548

0.0946

0.0784


Øz,a

103.56

103.46




 









 








* Derived here from Xaa and Xbb - Xcc = 5.4174(83) MHz.


** Theoretical value derived by Kannengießer, et al. [1].


*** Derived here from experimental inertial axes coupling constants.












 



Table 2.  N-Ethylacetamide:  MP2/6-311++G(d,p) and HF/6-311++G(3df,3pd) optimized structure parameters (Å and degrees).





 C
 N,1,B1
 C,2,B2,1,A1
 O,3,B3,2,A2,1,D1,0
 C,3,B4,2,A3,1,D2,0
 H,1,B5,2,A4,3,D3,0
 H,1,B6,2,A5,3,D4,0
 H,2,B7,1,A6,3,D5,0
 H,5,B8,3,A7,2,D6,0
 H,5,B9,3,A8,2,D7,0
 H,5,B10,3,A9,2,D8,0
 C,1,B11,2,A10,3,D9,0
 H,12,B12,1,A11,2,D10,0
 H,12,B13,1,A12,2,D11,0
 H,12,B14,1,A13,2,D12,0


      MP2      HF




 B1=1.4566035
 B2=1.36916148
 B3=1.22628734
 B4=1.51690446
 B5=1.09245499
 B6=1.09377993
 B7=1.00862652
 B8=1.09266237
 B9=1.09173934
 B10=1.09294516
 B11=1.52752798
 B12=1.09215931
 B13=1.09446172
 B14=1.09418287
 A1=120.8623724
 A2=122.22285799
 A3=115.56803279
 A4=107.17256988
 A5=107.57582129
 A6=118.89026694
 A7=113.29019519
 A8=108.44091591
 A9=108.50787818
 A10=112.77960113
 A11=109.83284966
 A12=110.41606327
 A13=110.68330925
 D1=-7.17811111
 D2=173.59678097
 D3=44.10089285
 D4=160.10990491
 D5=163.95614988
 D6=6.14865512
 D7=127.73829244
 D8=-115.33661297
 D9=-77.158974
 D10=59.98843411
 D11=179.66001492
 D12=-60.33243963
 B1=1.44939918
 B2=1.34850127
 B3=1.19586781
 B4=1.51198086
 B5=1.07876618
 B6=1.08278037
 B7=0.98929401
 B8=1.08149862
 B9=1.08010622
 B10=1.08229744
 B11=1.52276455
 B12=1.08174395
 B13=1.08401111
 B14=1.0844297
 A1=122.76339767
 A2=122.74138284
 A3=116.06537954
 A4=107.73713249
 A5=107.56552041
 A6=118.50976939
 A7=113.44263752
 A8=108.47703669
 A9=108.29050551
 A10=113.39252132
 A11=110.48761454
 A12=110.21469583
 A13=111.08057973
 D1=-3.06233001
 D2=176.74290307
 D3=36.42562497
 D4=152.26046522
 D5=172.86199509
 D6=10.18378526
 D7=132.13485803
 D8=-111.01390675
 D9=-85.59612011
 D10=60.60718459
 D11=-179.6752083
 D12=-59.88955147







 








 





Table 3.  N-Ethylacetamide: Rotational Constants (MHz). Calc = MP2/6-311++G(d,p) and  HF/6-311++G(3df,3pd) optimization.

 





Calc /MP2
Calc /HF   Expt [1]

 




 A
7093.
7486.
7270.2759(93)

 B
2213.
2157.
2183.5536(24)

 C
1969.
1932.
1938.7113(18)

 



 








 









[1] R.Kannengießer, M.J.Lach, W.Stahl, and H.V.L.Nguyen, ChemPhysChem 16(9),1906(2015).


 









 








Formamide
AcetamideN-Methylformamide
N-Dimethylformamide

N-Ethylformamide
N,N-Diethylacetamide
N-Methylacetamide
N,N-Dimethylacetamide

see Amides








 









 









Table of Contents




Molecules/Nitrogen




 








 













NEtacetamide.html






Last Modified 6 May 2015