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2,5-F2-C5H3N
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in
2,5-Difluoropyridine |
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Calculation of the
nitrogen nqcc's
in 2,5-difluoropyridine was made here on a molecular structure given by
B3P86/6-31G(3d,3p) optimization. These are compared with
experimental values [1] in Table 1. Structure parameters are
given in Table 2, atomic coordinates in Table 3, rotational
constants in Table 4, and quartic centrifugal distortion constants in
Table 5.
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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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RMS is the root mean square
difference between calculated and experimental diagonal coupling
constants. RSD
is the calibration residual standard deviation of the
B3PW91/6-311+G(df,pd) model for
calculation of the nqcc's.
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Table 1. Nitrogen nqcc's in
2,5-Difluoropyridine (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 |
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0.162 |
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0.1563(11) *
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Xbb |
- |
2.973 |
-
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3.0074(8) *
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Xcc |
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2.811 |
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2.8510(8) *
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|Xab| |
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2.713 |
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3.0(3)
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RMS
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0.031 (1.5 %)
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RSD |
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0.030 (1.3 %) |
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Xxx |
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1.728 |
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1.966
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Xyy |
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2.811 |
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2.851
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Xzz |
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4.539 |
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4.817
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ETA |
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0.239 |
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Øz,a |
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60.01 |
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58.9
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Øa,bi |
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58.48 |
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Øz,bi ** |
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1.53 |
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* Calculated here from experimental
1.5(Xaa) = 0.2345(16) MHz and 0.25(Xbb - Xcc)
= -1.4646(3) MHz using Kisiel's program
QDIAG.f. |
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** The z-axis makes an angle of
1.53o with the external bisector ( 'bi' ) of the
C(6)N(1)C(2) angle, and tilts toward C(6). |
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| Table 2.
2,5-Difluoropyridine. Molecular structure parameters, ropt
and rs [1] (Å and degrees). |
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ropt |
rs |
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N(1)C(2) |
1.3087 |
1.308(2) |
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C(2)C(3) |
1.3902 |
1.396(2) |
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C(3)C(4) |
1.3845 |
1.378(3) |
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C(4)C(5) |
1.3864 |
1.389(2) |
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C(5)C(6) |
1.3834 |
1.387(2) |
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C(6)N(1) |
1.3348 |
1.331(3) |
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C(2)F(2) |
1.3353 |
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C(3)H(3) |
1.0828 |
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C(4)H(4) |
1.0837 |
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C(5)F(5) |
1.3390 |
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C(6)H(6) |
1.0860 |
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C(6)N(1)C(2) |
117.20 |
117.1(3) |
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N(1)C(2)C(3) |
125.80 |
126.0(3) |
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C(2)C(3)C(4) |
117.05 |
117.0(3) |
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C(3)C(4)C(5) |
117.67 |
117.6(3) |
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C(4)C(5)C(6) |
120.55 |
120.7(2) |
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C(5)C(6)N(1) |
121.73 |
121.6(3) |
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N(1)C(2)F(2) |
116.06 |
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C(2)C(3)H(3) |
120.55 |
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C(3)C(4)H(4) |
122.06 |
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C(4)C(5)F(5) |
119.89 |
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C(5)C(6)H(6) |
120.41 |
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| Table 3.
2,5-Difluoropyridine. Atomic coordinates, ropt. |
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a (Å) |
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b (Å) |
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N(1) |
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0.7169 |
- |
1.1678 |
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C(2) |
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1.3126 |
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0.0025 |
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C(3) |
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0.6789 |
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1.2349 |
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C(4) |
- |
0.7056 |
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1.2332 |
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C(5) |
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1.3479 |
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0.0045 |
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C(6) |
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0.6179 |
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1.1706 |
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F(2) |
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2.6478 |
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0.0262 |
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H(3) |
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1.2580 |
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2.1498 |
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H(4) |
- |
1.2820 |
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2.1509 |
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F(5) |
- |
2.6859 |
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0.0489 |
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H(6) |
- |
1.1234 |
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2.1317 |
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| Table 4.
2,5-Difluoropyridine. Rotational Constants (MHz). |
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Calc ropt |
Expt. [1]
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A |
5873.4 |
5829.31413(10)
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B |
1484.1 |
1479.085663(27)
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C |
1184.7 |
1179.749450(24)
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Table
5. 2,5-Difluoropyridine. Quartic centrifugal distortion
constants (kHz). Calc = B3LYP/cc-pVTZ opt freq=vibrot
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Calc |
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Expt [1] |
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Delta_J
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0.0375
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0.03928(22)
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Delta_JK |
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0.0696
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0.0682(11)
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Delta_K |
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1.13
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1.149(14)
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delta_j |
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0.00859
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9.04(5)
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delta_k |
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0.155
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0.1579(25)
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[1] C.W.
van Dijk, M.Sun, and J. van Wijngaarden, J.Mol.Spectrosc. 280,34(2012). |
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Pyridine |
2-Fluoropyridine |
2,3-Difluoropyridine
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3-Fluoropyridine |
4-Fluoropyridine |
2,4-Difluoropyridine |
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2,6-Difluoropyridine |
3,4-Difluoropyridine |
3,5-Difluoropyridine |
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Table of Contents
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Molecules/Nitrogen |
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25DFP.html |
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Last
Modified 12 June 2012 |
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