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HC(=O)-N(H)-C6H5
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Nitrogen |
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Nuclear
Quadrupole Coupling Constants |
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in
cis-Formanilide
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Calculation of the
nitrogen nqcc's in formanilide was made here on molecular
structures given by MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p)
optimizations. These
are
compared with the
experimental nqcc's [1] in Table 1. Structure parameters in
Z-matrix format are
given here. Rotational
constants and dipole moments are given in Table 2.
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Note: The MP2 and B3LYP angles
between the
pseudo-peptidic group and the benzene ring are respectively ±44.3o and ±32.5o. |
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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. 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 cis-Formanilide
(MHz). Calculation was made on the (1) MP2/6-311+G(d,p) and (2)
B3LYP/6-311++G(d,p) 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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2.136 |
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2.111 |
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2.17 * |
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Xbb |
- |
0.048 |
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0.700 |
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0.59 * |
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Xcc |
- |
2.088 |
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2.811 |
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2.77 * |
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Xab |
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0.249 |
- |
0.224 |
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Xac |
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0.136 |
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0.141 |
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Xbc |
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2.651 |
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2.141 |
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RMS |
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0.54 (29. %) |
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0.08 (4.1 %) |
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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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1.733 |
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1.669 |
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Xyy |
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2.186 |
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2.164 |
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Xzz |
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3.919 |
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3.833 |
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ETA |
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0.116 |
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0.129 |
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* Derived here from (3/2)Xaa
= 3.26(2) and (1/4)(Xbb - Xcc) = 0.84(3) MHz. |
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| Table 2. cis-Formanilide.
Rotational constants (MHz) and B3PW91/6-311+G(df,pd)
calculated dipole moments (D). |
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ropt (1) =
MP2/6-311++G(d,p) optimization. |
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ropt (2)
= B3LYP/6-311++G(d,p) optimization. |
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Calc. ropt (1) |
Calc. ropt (2) |
Expt. [1] |
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A |
4982.4 |
5106.7 |
5061.76(5) |
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B |
926.4 |
922.2 |
929.1786(2) |
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C |
796.0 |
789.0 |
794.6967(2) |
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|µa| |
3.90 |
3.77 |
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|µb| |
0.34 |
0.25 |
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|µc| |
0.22 |
0.10 |
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[1] S.Blanco, J.C.López,
A.Lesarri, W.Caminati, and J.L.Alonso, Mol.Phys. 103,1473(2005).
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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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trans-Formanilide |
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Table of Contents |
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Molecules/Nitrogen |
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Formanilide_cis.html |
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Last
Modified 10 Jan 2011 |
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