N-Ethylacetamide

(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 r_opt 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 = (X_xx - X_yy)/X_zz. 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) r_opt structures.

		Calc /MP2		Calc /HF		Expt [1]

X_aa		1.720		1.782		1.7508(32)
X_bb		1.829		1.867		1.8333(45) *
X_cc	-	3.549	-	3.649	-	3.5841(45) *
X_ab		0.146	-	0.018		0.1686 **
X_ac		1.396		1.406	-	1.651(71)
X_bc	-	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 %)

X_xx		1.929		1.835		1.898(12) ***
X_yy		2.153		2.219		2.220(37)
X_zz	-	4.082	-	4.054	-	4.118(39)
ETA		0.0548		0.0946		0.0784
Ø_z,a		103.56		103.46

* Derived here from X_aa and X_bb - X_cc = 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).

N-Ethylformamide

N,N-Diethylacetamide

N-Methylacetamide

N,N-Dimethylacetamide

see Amides

Table of Contents

Molecules/Nitrogen

NEtacetamide.html

Last Modified 6 May 2015