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2,6-Cl2-C4N2H2
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Nitrogen and Chlorine
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Nuclear
Quadrupole Coupling Constants |
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in 2,6-Dichloropyrazine |
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The molecular structure of 2,6-dichloropyrazine
was optimized at the B3P86/6-31G(3d,3p) level of theory. C2V
symmetry was assumed. On this structure, calculation was
made of the nitrogen and chlorine nqcc's. The results are given in
Tables 1 and 2. Structure parameters are given in Table 3, atomic
coordinates in Table 4, and rotational constants in Table 5. |
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In Tables 1 and 2, subscripts a,b,c
refer to the principal axes of the inertia tensor. RSD
is the calibration residual standard deviation of the model for
calculation of the nqcc's.
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Table 1. Nitrogen nqcc's in 2,6-Dichloropyrazine (MHz). Calculation
was made on the B3P86/6-31G(3d,3p) ropt structure. |
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Calc. |
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Expt. |
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14N(1) |
Xaa |
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1.746 |
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Xbb |
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4.758 |
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Xcc |
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3.012 |
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ETA * |
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0.266 |
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14N(4) |
Xaa |
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1.209 |
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Xbb |
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5.208 |
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Xcc |
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4.000 |
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ETA * |
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0.536 |
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RSD |
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0.030 (1.3 %) |
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* ETA
= (Xaa - Xcc)/Xbb = (Xxx
- Xyy)/Xzz. |
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Table 2. Chlorine nqcc's in 2,6-Dichloropyrazine (MHz). Calculation
was made on the B3P86/6-31G(3d,3p) ropt structure. |
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Calc. |
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Expt. |
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35Cl(2,6) |
Xaa |
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42.98 |
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Xbb |
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12.12 |
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Xcc |
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30.85 |
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Xab |
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49.96 |
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RSD |
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0.49 (1.1 %) |
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Xxx |
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41.63 |
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Xyy |
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30.85 |
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Xzz |
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72.48 |
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ETA |
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0.149 |
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Øz,a |
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30.56 |
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Øa,CCl |
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30.31 |
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Øz,CCl |
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0.25 |
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37Cl(2,6) |
Xaa |
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33.87 |
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Xbb |
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9.56 |
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Xcc |
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24.32 |
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Xab |
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39.38 |
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RSD |
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0.44 (1.1 %) |
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| Table 3. Molecular structure parameters, ropt (Å
and degrees). |
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C(2)Cl(2) |
1.7268 * |
C(6)N(1)C(2) |
115.95 |
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N(1)C(2) |
1.3195 |
N(1)C(2)C(3) |
122.76 |
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C(2)C(3) |
1.3948 |
C(2)C(3)N(4) |
120.40 |
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C(3)C(4) |
1.3280 |
C(3)N(4)C(5) |
117.73 |
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C(3)H(3) |
1.0845 |
N(1)C(2)Cl(2) |
117.66 |
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C(2)C(3)H(3) |
121.24 |
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* In
chloropyrazine, CCl = 1.7327 Å. |
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| Table 4. Atomic coordinates, ropt. Normal species. |
| (More figures are shown than are significant.) |
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a (Å) |
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b (Å) |
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N(1) |
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0.0
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- |
0.671185 |
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C(2,6) |
± |
1.118677
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0.028485 |
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C(3,5) |
± |
1.136641
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1.423189 |
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N(4) |
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0.0
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2.109847 |
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Cl(2,6) |
± |
2.609393 |
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0.843095 |
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H(3,5) |
± |
2.071025
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1.973722 |
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| Table 5. Rotational Constants
(MHz). Normal species. |
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Calc ropt |
Expt. |
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A |
2890.5 |
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B |
925.8 |
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C |
701.2 |
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Pyrazine |
Pyridine |
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Pyrimidine |
1,3,5-Triazine |
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Chloropyrazine |
2,3-Difluoropyrazine |
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2,3-Dichloropyrazine |
2,6-Difluoropyrazine |
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Table of Contents
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Molecules/Nitrogen |
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Molecules/Chlorine |
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26DCPyrazine.html |
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Last
Modified 20 Nov 2003 |
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