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CH3CH2-O-C(=O)NH2
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in Ethyl Carbamate (urethane)
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Calculation was made of the nitrogen nqcc's on MP2/6-311+G(3df,3pd) optimized structures of each of the conformers shown below. Calculated and experimental
(for conformer II [1]) nqcc's are compared in Table 1. Structure parameters are given here in Z-matrix format. Rotational constants are given in Table 2.
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Conformer IIa
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Conformer IIb
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In Table 1, 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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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. |
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Table 1. Nitrogen
nqcc's in Urethane (MHz). Calculation was made on conformers IIa and IIb.
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Calc IIa
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Calc IIb |
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Expt. [1] |
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14N |
Xaa |
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1.458 |
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2.151
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1.8921(11) |
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Xbb |
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1.853 |
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2.018
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1.8922(22) |
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Xcc |
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3.311 |
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4.169
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3.7843(11) |
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Xab
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0.153 |
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0.210
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Xac
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2.243 |
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1.062
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Xbc
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1.051 |
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0.269
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RMS |
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0.37 (14.7 %) |
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0.28 (11.0 %)
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RSD |
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0.030 (1.3 %) |
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0.030 (1.3 %) |
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Xxx |
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1.896 |
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1.884
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Xyy |
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2.476 |
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2.467
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Xzz |
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4.372 |
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4.351
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ETA |
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0.133 |
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0.134
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Table 2. Urethane. Rotational constants (MHz).
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Calc IIa
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Calc IIb
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Expt. / Conf. II [1]
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A
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7588.3
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7519.2
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7565.417996(90)
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B
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2446.8
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2454.8
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2414.784375(28)
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C
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2135.2
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2148.9
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2116.375036(34)
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[1] R.A.Moyiyenko,
M.Goubet, J.Habinshuti, T.H.Huet, E.A.Alekseev, P.Asselin, and
P.Soulard, 62nd OSU International Symposium on Molecular Spectroscopy,
2007, Abstract WG14.
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K.M.Marstokk and H.M.Møllendal, Acta Chem.Scand. 53,329(1999).
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Urethane I
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Methylcarbamate
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Table of Contents |
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Molecules/Nitrogen |
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urethane_II.html |
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Last
Modified 16 Feb 2012
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