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C2H2N2Se
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Nitrogen |
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Nuclear
Quadrupole Coupling Constants |
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in 1,2,5-Selenadiazole |
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Calculation of the 14N nqcc
tensor in 1,2,5-selenadiazole was made here on molecular
structures given by B3PW91/6-31G(2d,2pd) and B3LYP/cc-pVTZ(G03)
optimization. These are compared with the experimental nqcc's [1]
in
Table 1. Structure parameters are given in Table 2. |
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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. The nqcc y-axis is chosen coincident with the
inertia c-axis, these are perpendicular to the molecular plane.
Ø (degrees) is the angle between its subscripted
parameters. ETA = (Xxx - Xyy)/Xzz. |
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RSD is the
calibration residual standard deviation of the B3PW91/6-311+G(df,pd)
model for calculation of nitrogen nqcc's. |
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Table 1. 14N(2,5) nqcc's in 1,2,5-Selenadiazole (MHz). Calculation was made
on molecular structures given by (1) B3PW91/6-31G(2d,2pd) and (2) B3LYP/cc-pVTZ optimization. |
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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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0.940 |
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0.905 |
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|Xaa| < 1 |
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Xcc - Xbb |
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5.382 |
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5.321 |
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5.2(3) |
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Xbb |
- |
3.161 |
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3.113 |
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Xcc |
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2.221 |
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2.208 |
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Xab |
± |
2.122 |
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2.227 |
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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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1.841 |
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1.900 |
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Xyy |
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2.221 |
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2.208 |
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Xzz |
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4.061 |
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4.104 |
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ETA |
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0.094 |
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0.076 |
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Øz,a |
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67.01 |
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66.03 |
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Øa,bi |
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79.90 |
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80.37 |
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Øz,bi * |
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12.88 |
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14.34 |
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* The z-axis makes an angle of Øz,bi with the external bisector ('bi') of the SeNC angle and tilts toward Se. |
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| Table 2. 1,2,5-Selenadiazole. Molecular structure parameters, ropt (Å
and degrees). |
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| ropt(1) = B3PW91/6-31G(2d,2pd) optimization. |
| ropt(2) = B3LYP/cc-pVTZ(G03) optimization. |
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| C2V |
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ropt(1) |
ropt(2) |
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SeN |
1.7879 |
1.8134 |
| NC |
1.3088 |
1.3034 |
| CC |
1.4347 |
1.4347 |
| CH |
1.0849 |
1.0838 |
| NSeN |
93.61 |
92.77 |
| SeNC |
106.59 |
106.49 |
| NCC |
116.60 |
117.12 |
| CCH |
124.18 |
123.55 |
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[1] G.L.Blackman, R.D.Brown, F.R.Burden, and J.E.Kent, Chem.Phys.Lett. 1,379(1967). |
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F.Hegelund, R.Wugt Larson, R.A.Aitken, and M.H.Palmer, J.Mol.Spectrosc. 236,189(2006). IR and theoretical study.
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Thiazole |
1,3,4-Oxadiazole |
1,2,5-Oxadiazole |
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1,2,3-Thiadiazole |
1,3,4-Thiadiazole |
1,2,4-Thiadiazole |
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1,2,5-Thiadiazole |
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Table of Contents |
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Molecules/Nitrogen |
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125SeDiazole.html |
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Last
Modified 19 Nov 2007 |
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