N,N-Dimethylpropionamide

CH₃CH₂-C(=O)N(CH₃)₂

Nitrogen

Nuclear Quadrupole Coupling Constants

in N,N-Dimethylpropionamide

¹⁴N nqcc's in N,N-dimethylpropionamide were determined by Kannengießer [1]. Calculation was made here of the ¹⁴N nqcc tensor on r_opt molecular structures derived by MP2/6-311++G(d,p) and HF/6-311++G(d,p) optimizations (assuming C_s symmetry). These are compared with the experimental nqcc's in Table 1. Structure parameters are given in Z-matrix format in Table 2. Rotational constants are compared 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.

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


Table 1. ¹⁴N nqcc's in N,N-Dimethylpropionamide (MHz). Calculation was made on the (1) MP2/6-311++G(d,p) and (2) HF/6-311++G(d,p) r_opt structures.

		Calc (1)		Calc (2)		Expt [1]

X_aa		2.119		2.108		2.0997(15)
X_bb - X_cc		7.137		7.226		7.2533(31)
X_bb		2.509		2.559		2.5768(34) *
X_cc	-	4.628	-	4.667	-	4.6765(34) *
\|X_ab\|		0.008		0.044

RMS		0.049 (1.6 %)		0.013 (0.41 %)
RSD		0.030 (1.3 %)		0.030 (1.3 %)

X_xx		2.119		2.104
X_yy		2.509		2.564
X_cc	-	4.628	-	4.667
ETA		0.0841		0.0985

* Calculated here from expermental X_aa and X_bb - X_cc


Table 2. N,N-Dimethylpropionamide. MP2/6-311++G(d,p) and HF/6-311++G(d,p) r_opt structure parameters. (Å and degrees).

		O C,1,B1 C,2,B2,1,A1 N,2,B3,1,A2,3,D1,0 C,4,B4,2,A3,1,D2,0 C,4,B5,2,A4,1,D3,0 H,3,B6,2,A5,1,D4,0 H,3,B7,2,A6,1,D5,0 H,5,B8,4,A7,2,D6,0 H,5,B9,4,A8,2,D7,0 H,5,B10,4,A9,2,D8,0 H,6,B11,4,A10,2,D9,0 H,6,B12,4,A11,2,D10,0 H,6,B13,4,A12,2,D11,0 C,3,B14,2,A13,1,D12,0 H,15,B15,3,A14,2,D13,0 H,15,B16,3,A15,2,D14,0 H,15,B17,3,A16,2,D15,0

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

	B1=1.22929032 B2=1.52773775 B3=1.3746377 B4=1.45068827 B5=1.45343623 B6=1.09635083 B7=1.09635083 B8=1.09707619 B9=1.08727236 B10=1.09707619 B11=1.09628005 B12=1.08865167 B13=1.09628005 B14=1.52549856 B15=1.09151493 B16=1.09382117 B17=1.09151493 A1=121.00536422 A2=121.96153281 A3=125.54876096 A4=119.50770276 A5=109.11929588 A6=109.11929588 A7=110.14915416 A8=111.41345752 A9=110.14915416 A10=110.16310206 A11=108.7461245 A12=110.16310206 A13=111.49158569 A14=110.72671068 A15=110.10180536 A16=110.72671068 D1=180. D2=180. D3=0. D4=-121.91694883 D5=121.91694883 D6=120.37408277 D7=0. D8=-120.37408277 D9=120.07084542 D10=0. D11=-120.07084542 D12=0. D13=59.57998281 D14=180. D15=-59.57998281	B1=1.20004084 B2=1.52412575 B3=1.36070431 B4=1.44653621 B5=1.45016217 B6=1.0867559 B7=1.0867559 B8=1.08740159 B9=1.0769886 B10=1.08740159 B11=1.08743372 B12=1.07658193 B13=1.08743372 B14=1.52406577 B15=1.08309636 B16=1.08622671 B17=1.08309636 A1=120.39748498 A2=121.79606201 A3=125.72639619 A4=119.66526697 A5=108.82516049 A6=108.82516049 A7=110.27677349 A8=112.06486004 A9=110.27677349 A10=110.24735345 A11=109.68457999 A12=110.24735345 A13=112.49469695 A14=111.14157114 A15=109.72415869 A16=111.14157114 D1=180. D2=180. D3=0. D4=-122.18370409 D5=122.18370409 D6=120.43039242 D7=0. D8=-120.43039242 D9=120.24786408 D10=0. D11=-120.24786408 D12=0. D13=59.90056872 D14=180. D15=-59.90056872


Table 3. N,N-Dimethylpropionamide. MP2/6-311++G(d,p) and HF/6-311++G(d.p) r_opt and Experimental Rotational Constants (MHz).

		MP2	HF	Expt [1]

	A	4693.	4800.	4691.96187(43)
	B	1813.	1816.	1826.88254(22)
	C	1352.	1362.	1358.78256(17)

[2] Raphaela Kannengießer, "Structures and Dynamics of Formamides, Acetamides, and Propionamides" Dissertation, RWTH Aachen University, Institute of Physical Chemistry, 2017.

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Molecules/Nitrogen

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Last Modified 15 Jan 2018