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2,4-F2-C5H3N
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in
2,4-Difluoropyridine |
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Calculation of the
nitrogen nqcc's
in 2,4-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
2,4-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 |
- |
2.977 |
-
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2.9921(11) *
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Xbb |
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0.486 |
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0.4445(11) *
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Xcc |
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2.491 |
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2.5477(11) *
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|Xab| |
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2.524 |
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2.55(6)
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RMS
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0.041 (2.1 %)
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RSD |
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0.030 (1.3 %) |
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Xxx |
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1.815 |
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1.801(50) *
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Xyy |
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2.491 |
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2.5477(11) *
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Xzz |
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4.306 |
-
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4.349(50) *
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ETA |
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0.157 |
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0.172(12) *
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Øz,a |
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27.78 |
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28.0(3) *
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Øa,bi |
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27.30 |
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Øz,bi ** |
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0.48 |
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* Calculated here from experimental
1.5(Xaa) = -4.4882(16) MHz and 0.25(Xbb - Xcc)
= -0.5258(5) MHz using Kisiel's program
QDIAG.f. |
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** The z-axis makes an angle of
0.48o 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.
2,4-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) |
1.3092 |
1.299(6) |
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C(2)C(3) |
1.3893 |
1.389(12) |
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C(3)C(4) |
1.3805 |
1.389(12) |
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C(4)C(5) |
1.3879 |
1.378(7) |
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C(5)C(6) |
1.3851 |
1.38(2) |
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C(6)N(1) |
1.3374 |
1.358(19) |
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C(2)F(2) |
1.3329 |
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C(3)H(3) |
1.0816 |
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C(4)F(4) |
1.3329 |
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C(5)H(5) |
1.0821 |
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C(6)H(6) |
1.0863 |
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C(6)N(1)C(2) |
116.38 |
115.7(17) |
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N(1)C(2)C(3) |
126.40 |
127.5(14) |
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C(2)C(3)C(4) |
115.14 |
114.0(11) |
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C(3)C(4)C(5) |
121.39 |
122.1(12) |
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C(4)C(5)C(6) |
116.65 |
116.8(17) |
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C(5)C(6)N(1) |
124.04 |
124.(2) |
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N(1)C(2)F(2) |
116.09 |
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C(2)C(3)H(3) |
122.33 |
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C(3)C(4)F(4) |
119.11 |
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C(4)C(5)H(5) |
120.97 |
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C(5)C(6)H(6) |
120.13 |
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| Table 3.
2,4-Difluoropyridine. Atomic coordinates, ropt. |
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a (Å) |
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b (Å) |
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N(1) |
- |
1.2444 |
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1.0504 |
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C(2) |
- |
1.1413 |
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0.2547 |
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C(3) |
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0.0383 |
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0.9885 |
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C(4) |
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1.1964 |
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0.2371 |
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C(5) |
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1.1580 |
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1.1502 |
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C(6) |
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0.0966 |
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1.7370 |
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F(2) |
- |
2.2886 |
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0.9333 |
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H(3) |
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0.0467 |
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2.0701 |
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F(4) |
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2.3743 |
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0.8612 |
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H(5) |
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2.0701 |
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1.7325 |
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H(6) |
- |
0.1925 |
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2.8191 |
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| Table 4.
2,4-Difluoropyridine. Rotational Constants (MHz). |
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Calc ropt |
Expt. [1]
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A |
3988.6 |
3965.04713(16)
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B |
1794.2 |
1787.44610(5)
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C |
1237.5 |
1231.91930(4)
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Table
5. 2,4-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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0.0639
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0.0656(4)
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Delta_JK |
-
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0.0165
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-
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0.0102(22)
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Delta_K |
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0.707
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0.712(9)
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delta_j |
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0.0218
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0.02232(26)
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delta_k |
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0.139
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0.148(5)
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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 |
2,5-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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24DFP.html |
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Last
Modified 12 June 2012 |
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