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2,3-F2-C5H3N
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in
2,3-Difluoropyridine |
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Calculation of the
nitrogen nqcc's
in 2,3-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
2,3-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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1.685 |
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1.6577(8) *
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Xbb |
- |
4.498 |
-
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4.5980(7) *
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Xcc |
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2.813 |
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2.9404(7) *
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|Xab| |
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0.035 |
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RMS
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0.095 (3.1 %)
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RSD |
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0.030 (1.3 %) |
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Xxx |
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1.685 |
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Xyy |
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2.813 |
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Xzz |
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4.498 |
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ETA |
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0.251 |
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Øz,a |
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0.33 |
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Øa,bi |
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0.18 |
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Øz,bi ** |
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0.51 |
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* Calculated here from experimental
1.5(Xaa) = 2.4865(12) MHz and 0.25(Xbb - Xcc)
= -1.88460(27) MHz using Kisiel's program
QDIAG.f.
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** The z-axis makes an angle of 0.51o
with the external bisector ( 'bi' ) of the C(6)N(1)C(2) angle, and
tilts toward C(2). |
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| Table 2.
2,3-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) |
1.3043 |
1.300(4) |
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C(2)C(3) |
1.3944 |
1.381(3) |
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C(3)C(4) |
1.3784 |
1.373(4) |
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C(4)C(5) |
1.3929 |
1.403(2) |
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C(5)C(6) |
1.3854 |
1.386(3) |
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C(6)N(1) |
1.3378 |
1.349(2) |
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C(2)F(2) |
1.3290 |
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C(3)F(3) |
1.3329 |
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C(4)H(4) |
1.0840 |
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C(5)H(5) |
1.0834 |
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C(6)H(6) |
1.0858 |
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C(6)N(1)C(2) |
117.72 |
116.9(5) |
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N(1)C(2)C(3) |
123.87 |
124.7(5) |
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C(2)C(3)C(4) |
118.66 |
119.3(4) |
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C(3)C(4)C(5) |
118.01 |
117.3(4) |
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C(4)C(5)C(6) |
118.62 |
118.7(3) |
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C(5)C(6)N(1) |
123.11 |
123.0(4) |
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N(1)C(2)F(2) |
117.74 |
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C(2)C(3)F(3) |
120.07 |
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C(3)C(4)H(4) |
119.52 |
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C(4)C(5)H(5) |
120.78 |
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C(5)C(6)H(6) |
120.97 |
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| Table 3.
2,3-Difluoropyridine. Atomic coordinates, ropt. |
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a (Å) |
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b (Å) |
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N(1) |
- |
0.7278 |
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1.3611 |
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C(2) |
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0.3907 |
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0.6902 |
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C(3) |
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0.4617 |
- |
0.7023 |
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C(4) |
- |
0.7126 |
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1.4241 |
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C(5) |
- |
1.9139 |
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0.7191 |
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C(6) |
- |
1.8707 |
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0.6656 |
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F(2) |
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1.5262 |
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1.3808 |
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F(3) |
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1.6477 |
- |
1.3107 |
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H(4) |
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0.6736 |
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2.5074 |
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H(5) |
- |
2.8631 |
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1.2412 |
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H(6) |
- |
2.7838 |
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1.2530 |
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| Table 4.
2,3-Difluoropyridine. Rotational Constants (MHz). |
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Calc ropt |
Expt. [1]
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A |
3330.0 |
3315.34829(12)
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B |
2337.4 |
2327.53363(7)
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C |
1373.4 |
1367.32191(4)
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Table
5. 2,3-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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0.0864
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0.0877(9)
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Delta_JK |
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0.0291
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0.042(5)
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Delta_K |
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0.682
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0.688(8)
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delta_j |
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0.0305
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0.0305(5)
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delta_k |
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0.0971
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0.105(3)
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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 |
2,4-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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23DFP.html |
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Last
Modified 12 June 2012 |
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