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2-Br-NC5H4 |
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Bromine and Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in 2-Bromopyridine |
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Nitrogen and bromine
nqcc's in 2-bromopyridine were calculated on a structure given by
B3P86/6-31G(3d,3p) optimization. Calculated
and experimental [1] nqcc's are compared in Tables 1 - 3. Structure
parameters are given in Table 4, atomic coordinates in Table 5, and
rotational constants in Table 6. |
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In Tables 1 - 3, 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.
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. Bromine nqcc's in 2-79Bromopyridine (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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79Br |
Xaa |
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554.08 |
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551.750(23) |
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Xbb |
- |
308.38 |
- |
304.172(15) |
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Xcc |
- |
245.69 |
- |
247.578(15) |
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Xab |
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- 1.24 |
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RMS |
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2.54 (0.69 %) |
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RSD |
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1.58 (0.39 %) |
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Xxx |
- |
308.39 |
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Xyy |
- |
245.69 |
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Xzz |
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554.08 |
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ETA |
- |
0.113 |
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Øz,a |
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0.08 |
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Øa,CBr |
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0.24 |
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Øz,CBr |
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0.16 |
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Table 2. Nitrogen nqcc's in 2-79Bromopyridine (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 |
- |
0.021 |
-
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0.084(12)
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Xbb |
- |
3.036 |
-
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3.005(8)
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Xcc |
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3.057 |
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3.089(8)
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Xab |
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2.880 |
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2.99(28)
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RMS
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0.045 (2.2 %)
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RSD |
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0.030 (1.3 %) |
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Xxx |
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1.722 |
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Xyy |
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3.057 |
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Xzz |
- |
4.779 |
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ETA |
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0.279 |
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Øz,a |
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58.82 |
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Øa,bi |
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58.12 |
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Øz,bi * |
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0.69 |
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* The z-axis makes an angle of 0.69o
with the external bisector ( 'bi' ) of the C(6)N(1)C(2)
angle, and tilts toward C(6). |
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Table 3. Bromine and Nitrogen nqcc's in 2-81Bromopyridine (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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81Br |
Xaa |
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462.92 |
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460.899(23)
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Xbb |
- |
257.65 |
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254.098(15)
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Xcc |
- |
205.27 |
- |
206.801(15)
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Xab |
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- 1.02 |
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RMS |
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2.53 (0.82 %)
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RSD |
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1.38 (0.40 %) |
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14N |
Xaa |
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0.021
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-
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0.089(12)
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Xbb |
- |
3.036
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- |
3.001(8)
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Xcc |
- |
3.057
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3.091(8)
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Xab |
-
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2.880
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2.73(34)
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RMS |
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0.049 (2.4 %)
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RSD |
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0.030 (1.3 %) |
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| Table 4. 2-Bromopyridine and Pyridine. Molecular structure parameters,
ropt (Å and degrees). |
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Pyridine |
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N(1)C(2) |
1.3152 |
1.3336 |
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C(2)C(3) |
1.3909 |
1.3904 |
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C(3)C(4) |
1.3855 |
1.3885 |
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C(4)C(5) |
1.3901 |
1.3885 |
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C(5)C(6) |
1.3873 |
1.3904 |
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C(6)N(1) |
1.3355 |
1.3336 |
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C(2)Br |
1.8859 |
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C(3)H(3) |
1.0818 |
1.0845 |
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C(4)H(4) |
1.0848 |
1.0851 |
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C(5)H(5) |
1.0834 |
1.0845 |
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C(6)H(6) |
1.0869 |
1.0880 |
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C(6)N(1)C(2) |
117.16 |
117.03 |
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N(1)C(2)C(3) |
124.74 |
123.80 |
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C(2)C(3)C(4) |
117.37 |
118.44 |
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C(3)C(4)C(5) |
119.13 |
118.50 |
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C(4)C(5)C(6) |
118.09 |
118.44 |
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C(5)C(6)N(1) |
123.51 |
123.80 |
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N(1)C(2)Br |
116.95 |
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C(2)C(3)H(3) |
120.76 |
120.21 |
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C(3)C(4)H(4) |
120.11 |
120.75 |
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C(4)C(5)H(5) |
121.51 |
121.35 |
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C(5)C(6)H(6) |
120.73 |
120.26 |
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| Table 5. 2-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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0.8680 |
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1.1783 |
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C(2) |
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0.2770 |
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0.0034 |
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C(3) |
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0.9418 |
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1.2184 |
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C(4) |
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2.3270 |
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1.1896 |
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C(5) |
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2.9785 |
- |
0.0383 |
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C(6) |
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2.2034 |
- |
1.1889 |
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Br(2) |
- |
1.6089 |
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0.0046 |
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H(3) |
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0.3897 |
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2.1487 |
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H(4) |
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2.8905 |
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2.1166 |
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H(5) |
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4.0598 |
- |
0.1055 |
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H(6) |
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2.6679 |
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2.1716 |
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| Table 6. 2-Bromopyridine. Rotational Constants
(MHz). Normal species. |
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Calc. ropt |
Expt. [1] |
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A |
5935.0 |
5869.9332(16)
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B |
1034.6 |
1026.14509(25)
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C |
881.0 |
873.37531(20)
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[1]
A.Y.Chung, E.A.Arsenault, S.L.Stephens, W.C.Pringle, C.A.Jiménez-Hoyos,
S.A.Cooke, and S.E.Novick, J.Mol.Spectrosc. 356,28(2019).
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A.Y.Chung, E.A.Arsenault, and S.E.Novick, Abstract FB06, 72nd ISMS, Champaign-Urbana, Illinois, 2017.
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W.Caminati and P.Forti, Chem.Phys.Lett. 15,343(1972): For 79Br, Xaa = 552.2(12) MHz and Xbb = -304.4(6) MHz; and for 81Br, Xaa = 460.4(20) MHz and Xbb = -252.6(7) MHz. |
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Pyrimidine |
Pyridine |
Pyrazine |
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3-Bromopyridine |
2-Chloropyridine |
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4-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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2MBrP.html |
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Last
Modified 29 Dec 2018 |
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