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4-Br-C5NH4
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Nitrogen and Bromine
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Nuclear
Quadrupole Coupling Constants |
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in 4-Bromopyridine |
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Nitrogen and bromine
nqcc's in 4-bromopyridine were calculated on a structure given by
B3P86/6-31G(3d,3p) optimization. Calculated and experimental (for Br [1]) nqcc's are shown in Table 1. Structure
parameters are given in Table 2, atomic coordinates in Table 3, and
rotational constants in Table 4. |
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In Tables 1 and 2, 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.
RMS is the root mean square difference between calculated and
experimental diagonal nqcc's (percent of average absolute experimental
nqcc). RSD
is the calibration residual standard deviation of the model for
calculation of the nqcc's.
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Table 1. Nitrogen and Bromine nqcc's in 4-Bromopyridine (MHz). Calculation
was made on the B3P86/6-31G(3d,3p) ropt structure. |
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Calc. |
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Expt. [1] |
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14N |
Xaa |
- |
4.859 |
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Xbb |
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1.492 |
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Xcc |
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3.367 |
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ETA * |
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0.386 |
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RSD |
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0.030 (1.3 %) |
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79Br |
Xaa |
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563.79 |
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557.5(13) |
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Xbb |
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304.69 |
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300.5(6) |
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Xcc |
- |
259.10 |
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257.0 |
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ETA * |
- |
0.0809 |
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RMS |
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4.5 (1.2 %) |
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RSD |
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1.58 (0.39 %) |
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81Br |
Xaa |
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471.03 |
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475.4(16) |
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Xbb |
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254.56 |
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254.1(6) |
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Xcc |
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216.47 |
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221.3 |
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ETA * |
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0.0809 |
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RMS |
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3.8 (1.2 %) |
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RSD |
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1.38 (0.40 %) |
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* ETA = (Xbb
- Xcc)/Xaa = (Xxx - Xyy)/Xzz. |
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| Table 2. 4-Bromopyridine and Pyridine. Molecular structure parameters,
ropt (Å and degrees). |
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Pyridine |
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N(1)C(2) |
1.3321 |
1.3336 |
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C(2)C(3) |
1.3898 |
1.3904 |
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C(3)C(4) |
1.3861 |
1.3885 |
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C(2)H(2) |
1.0875 |
1.0880 |
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C(3)H(3) |
1.0821 |
1.0845 |
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C(4)Br |
1.8724 |
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C(6)N(1)C(2) |
116.79 |
117.03 |
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N(1)C(2)C(3) |
124.16 |
123.80 |
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C(2)C(3)C(4) |
117.77 |
118.44 |
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C(3)C(4)C(5) |
119.35 |
118.50 |
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N(1)C(2)H(2) |
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115.94 |
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C(2)C(3)H(3) |
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120.21 |
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| Table 3. 4-Bromopyridine. Atomic coordinates, ropt. Normal species. |
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a (Å) |
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b (Å) |
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N(1) |
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3.0182 |
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0.0 |
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C(2,6) |
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2.3282 |
± |
1.1345 |
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C(3,5) |
- |
0.9298 |
± |
1.1965 |
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C(4) |
- |
0.2299 |
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0.0 |
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H(2,6) |
- |
2.8987 |
± |
2.0541 |
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H(3,5) |
- |
0.4163 |
± |
2.1490 |
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Br(4) |
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1.6426 |
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0.0 |
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| Table 4. 4-Bromopyridine. Rotational Constants
(MHz). Normal species. |
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Calc. ropt |
Expt. [1] |
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A |
6084.3 |
6016.0(12) |
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B |
994.9 |
986.902(6) |
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C |
855.1 |
847.769(8) |
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[1] W.Caminati and P.Forti, Chem.Phys.Lett. 15,343(1972). |
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Pyrimidine |
Pyridine |
Pyrazine |
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2-Bromopyridine |
2-Chloropyridine |
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3-Bromopyridine |
3-Chloropyridine |
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2-Fluoropyridine |
4-Fluoropyrimidine |
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Table of Contents
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Molecules/Nitrogen |
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Molecules/Bromine |
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4MBrP.html |
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Last
Modified 6 Dec 2003 |
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