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2,6-F2-C5H3N
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in
2,6-Difluoropyridine |
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Calculation of the
nitrogen nqcc's in 2,6-difluoropyridine was made on the substitution
structure of Stiefvater [1], and on a
structure obtained by optimization at the B3P86/6-31G(3d,3p) level of
theory.
These are compared in Tables 1 and 2 with the experimental nqcc's
of Dijk et al. [2]. Structure parameters are compared in Table
3. Substitution coordinates are given in Table 4.
Rotational constants are compared in Table 5, quartic centrifugal
distortion constants in Table 6.
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Subscripts a,b,c
refer to the principal axes of the inertia tensor; x,y,z to the
principal axes of the nqcc tensor. RMS is the root mean square
difference between calculated and experimental nqcc's. 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
2,6-Difluoropyridine (MHz). Calculation
was made on the substitution structure [1]. |
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Calc. |
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Expt. [2] |
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14N |
Xaa |
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1.849 |
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1.8423(11) *
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Xbb |
- |
3.965 |
- |
4.1010(11) *
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Xcc |
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2.116 |
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2.2586(11) *
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ETA ** |
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0.067 |
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RMS |
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0.114 (4.2 %) |
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RSD |
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0.030 (1.3 %) |
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* Calculated here from experimental
1.5(Xaa) = 2.7635(16) MHz and 0.25(Xbb - Xcc)
= -1.5899(5) MHz using Kisiel's program
QDIAG.f. |
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** ETA = (Xaa - Xcc)/Xbb
= (Xxx - Xyy)/Xzz. |
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Table 2. Nitrogen nqcc's in
2,6-Difluoropyridine (MHz). Calculation
was made on the B3P86/6-31G(3d,3p) ropt structure. |
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Calc. |
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Expt. [2] |
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14N |
Xaa |
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1.897 |
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1.8423(11) * |
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Xbb |
- |
4.049 |
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4.1010(11) * |
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Xcc |
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2.152 |
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2.2586(11) * |
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ETA ** |
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0.063 |
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RMS |
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0.075 (2.8 %) |
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RSD |
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0.030 (1.3 %) |
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* Calculated here from experimental
1.5(Xaa) = 2.7635(16) MHz and 0.25(Xbb - Xcc)
= -1.5899(5) MHz using Kisiel's program
QDIAG.f. |
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** ETA = (Xaa - Xcc)/Xbb
= (Xxx - Xyy)/Xzz. |
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| Table 3.
2,6-Difluoropyridine. Molecular structure parameters, rs
and ropt (Å and degrees). |
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rs [1] |
ropt |
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N(1)C(2) |
1.3168(17) |
1.3138 |
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C(2)C(3) |
1.3767(10) |
1.3860 |
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C(3)C(4) |
1.3941(5) |
1.3887 |
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C(2)F(2) |
1.347(1) |
1.3315 |
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C(3)H(3) |
1.0795(7) |
1.0818 |
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C(4)H(4) |
1.0822(5) |
1.0844 |
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C(6)N(1)C(2) |
115.0(3) |
115.93 |
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N(1)C(2)C(3) |
126.5(1) |
125.70 |
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C(2)C(3)C(4) |
116.1(1) |
116.37 |
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C(3)C(4)C(5) |
119.8(1) |
119.94 |
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N(1)C(2)F(2) |
114.7(1) |
115.62 |
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C(2)C(3)H(3) |
120.8(1) |
120.60 |
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C(3)C(4)H(4) |
120.1(1) |
120.03 |
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| Table 4.
2,6-Difluoropyridine. Atomic coordinates, rs [1]. |
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a (Å) |
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b (Å) |
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N(1) |
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0.0 |
- |
0.9437 |
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C(2,6) |
± |
1.1100 |
- |
0.2353 |
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C(3,5) |
± |
1.2058 |
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1.1376 |
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C(4) |
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0.0 |
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1.8368 |
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F(2,6) |
± |
2.2420 |
- |
0.9659 |
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H(3,5) |
± |
2.1690 |
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1.6251 |
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H(4) |
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0.0 |
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2.9192 |
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| Table 5.
2,6-Difluoropyridine. Rotational Constants (MHz). |
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Calc ropt |
Calc rs * |
Expt. [2] |
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A |
3770.6 |
3751.7 |
3747.68671(7) |
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B |
1911.8 |
1907.5 |
1905.82582(5) |
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C |
1268.6 |
1264.6 |
1263.24839(5) |
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* Calculated here. |
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Table 6.
2,6-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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0.0673
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0.0700(5)
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Delta_JK |
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0.00782
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0.0170(10)
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Delta_K |
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0.567
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0.5565(22)
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delta_j |
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0.0238
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0.02424(14)
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delta_k |
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0.137
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0.1406(14)
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[1] O.L.Stiefvater, Z.Naturforsch.
30a,1765(1975). |
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[2] C.W. van Dijk, M.Sun, and J. van
Wijngaarden, J.Mol.Spectrosc. 280,34(2012). |
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S.Doraiswamy and S.D.Sharma, Chem.
Phys.Lett. 37,527(1976): Xaa = 1.91(4), Xbb
= -4.24(4), and Xcc = 2.33(10) MHz. |
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O.L.Stiefvater,
S.Lui, and J.A.Ladd, Z.Naturforsch. 31a,53(1976): Xaa
= 1.82(5), Xbb = -4.16(2), and Xcc
= 2.34(5) MHz. |
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D.Hübner, M.Stolze, and D.H.Sutter, Z.Naturforsch. 36a,332(1981): Xaa = 1.91(4), Xbb
= -4.12(6), and Xcc = 2.21(6) MHz.
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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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3,4-Difluoropyridine |
3,5-Difluoropyridine |
2,5-Difluoropyridine |
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2,6-Dichloropyridine |
2,6-Lutidine |
2,6-Dicyanopyridine |
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Table of Contents
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Molecules/Nitrogen |
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26DFPYR.html |
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Last
Modified 12 June 2012 |
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