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CH3CH2-C(=O)-N(H)CH3
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Nitrogen |
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Nuclear
Quadrupole Coupling Constants |
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in N-Methylpropionamide
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Calculation of the
nitrogen nqcc's in N-methylpropionamide was made here on molecular
structures given by HF/6-311++G(3df,3pd) and HF/aug-cc-pVTZ(G03) optimizations, with Cs symmetry assumed ("NMPA was found to have an almost planar skeleton" [1]). These are
compared with the
experimental nqcc's [1] in Table 1. Structure parameters are
given in Table 2, rotational constants in Table 3.
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In Table 1, subscripts a,b,c refer to the
principal axes of the inertia tensor; subscripts x,y,z to the principal axes
of the nqcc tensor. Ø (degrees) is the angle between its subscripted
parameters. ETA = (Xxx - Xyy)/Xzz. |
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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 nqcc's.
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Table 1. 14N nqcc's in N-Methylpropionamide (MHz). Calculation was made
on the (1) HF/6-311++G(3df,3pd) and (2) HF/aug-cc-pVTZ(G03) optimized structures. |
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Calc. (1)
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Calc. (2) |
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Expt. [1] |
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Xaa |
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2.291 |
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2.294 |
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2.270(24) |
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Xbb |
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2.047 |
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2.042 |
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1.8975 * |
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Xcc |
- |
4.338 |
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4.336 |
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4.1675 * |
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|Xab| |
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0.301 |
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0.300 |
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0.32(17) |
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RMS |
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0.132 (4.7 %) |
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0.129 (4.6 %) |
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RSD |
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0.030 (1.3 %) |
0.030 (1.3 %) |
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Xxx |
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1.844 |
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1.843 |
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Xyy |
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2.494 |
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2.494 |
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Xzz |
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4.338 |
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4.336 |
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ETA |
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0.150 |
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0.150 |
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* Derived here from the experimental Xaa and Xbb - Xcc = 6.065(29) MHz. |
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| Table 2. N-Methylpropionamide. Heavy atom structure parameters (Å
and degrees). Complete structures are given here in Z-Matrix format. |
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ropt (1) = HF/6-311++G(3df,3pd) optimization. |
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ropt (2) = HF/aug-cc-pVTZ(G03) optimization. |
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| Point Group: Cs |
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ropt (1) |
ropt (2) |
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C(1)N(2) |
1.4445 |
1.4450 |
| N(2)H(9) |
0.9887 |
0.9885 |
| N(2)C(3) |
1.3496 |
1.3498 |
| C(3)O(4) |
1.1949 |
1.1964 |
| C(3)C(5) |
1.5187 |
1.5188 |
| C(5)C(12) |
1.5207 |
1.5207 |
| C(1)N(2)C(3) |
121.90 |
121.97 |
| C(1)N(2)H(9) |
119.09 |
119.06 |
| N(2)C(3)O(4) |
121.95 |
121.94 |
| N(2)C(3)C(5) |
115.03 |
115.03 |
| C(3)C(5)C(12) |
113.24 |
113.29 |
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| Table 3. N-Methylpropionamide. Rotational Constants (MHz). Normal Species. |
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ropt (1) = HF/6-311++G(3df,3pd) optimization. |
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ropt (2) = HF/aug-cc-pVTZ(G03) optimization. |
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Calc. ropt (1) |
Calc. ropt (2) |
Expt. |
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A |
9638.4 |
9626.1 |
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B |
2068.1 |
2066.5 |
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C |
1757.2 |
1755.7 |
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[1] Y.Kawashima, R.D.Suenram, and E.Hirota, J.Mol.Spectrsoc. 219,105(2003).
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Formamide |
Acetamide |
N-Ethylformamide |
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N-Acetylglycine |
Dimethylamine |
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N-Methylacetamide |
Propionamide |
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Table of Contents |
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Molecules/Nitrogen |
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NMPA.html |
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Last
Modified 27 June 2006 |
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