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Nicotinic
Acid |
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cis-Nicotinic
Acid
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trans-Nicotinic
Acid |
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in Nicotinic
Acid
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(Pyridine-3-Carboxylic
Acid) |
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Calculation of the N nqcc's in
nicotinic acid was made here on molecular structures derived by
B3P86/6-31G(d,p) and B3P86/6-31G(3d,3p)
optimizations. Calculated and experimental nqcc's [1] are
compared in
Tables 1 and 2. Structure parameters are given in Table 3,
rotational constants in Table 4. |
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In Tables 1 and 2, subscripts a,b,c
refer to the
principal axes of the inertia tensor; x,y,z to the principal axes
of the nqcc tensor.
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 nqcc's (percent
of the average of the absolute experimental nqcc's). RSD is the
calibration residual standard deviation of
the B3PW91/6-311+G(df,pd) model for calculation of nitrogen nqcc's,
which may be taken as an estimate of the uncertainty in the
calculated nqcc's. |
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Table 1. 14N nqcc's in
cis-Nicotinic Acid (MHz). Calculation was made on (1)
B3P86/6-31G(d,p) and (2) B3P86/6-31G(3d,3p) optimized structures. |
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Calc. (1)
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Calc. (2) |
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Expt. [1] |
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Xaa |
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0.003 |
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0.002 |
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0.0361(87) |
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Xbb |
- |
3.429 |
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3.446 |
- |
3.4585(96) |
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Xcc |
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3.426 |
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3.444 |
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3.4223(96) |
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|Xab| |
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2.710 |
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2.700 |
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RMS |
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0.026 (1.1 %) |
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0.025 (1.1 %) |
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RSD |
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0.030 (1.3 %) |
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0.030 (1.3 %) |
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Xxx |
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1.494 |
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1.481 |
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Xyy |
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3.426 |
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3.444 |
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Xzz |
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4.920 |
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4.926 |
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ETA |
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0.392 |
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0.399 |
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Øz,a |
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61.17 |
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61.28 |
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Øa,bi * |
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61.00 |
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61.11 |
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Øz,bi |
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0.18 |
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0.17 |
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* "bi" is the bisector of the CNC
angle. |
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Table 2. 14N nqcc's in
trans-Nicotinic Acid (MHz). Calculation was made on (1)
B3P86/6-31G(d,p) and (2) B3P86/6-31G(3d,3p) optimized structures. |
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Calc. (1)
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Calc. (2) |
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Expt. [1] |
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Xaa |
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0.172 |
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0.193 |
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0.1907(83) |
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Xbb |
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3.279 |
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3.274 |
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3.2621(91) |
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Xcc |
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3.451 |
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3.467 |
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3.4527(91) |
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|Xab| |
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2.809 |
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2.814 |
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RMS |
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0.015 (0.63 %) |
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0.011 (0.48 %) |
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RSD |
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0.030 (1.3 %) |
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0.030 (1.3 %) |
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Xxx |
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1.484 |
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1.475 |
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Xyy |
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3.451 |
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3.467 |
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Xzz |
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4.935 |
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4.942 |
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ETA |
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0.398 |
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0.403 |
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Øz,a |
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59.47 |
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59.35 |
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Øa,bi * |
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59.53 |
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59.42 |
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Øz,bi |
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0.06 |
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0.07 |
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* "bi" is the bisector of the CNC
angle. |
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| Table 3.
Nicotinic Acid. Selected structure parameters (Å
and degrees). Complete structures are given here in Z-matrix format. |
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ropt (1) =
B3P86/6-31G(d,p) optimization. |
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ropt (2) =
B3P86/6-31G(3d,3p) optimization. |
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| cis-Nicotinic
Acid |
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ropt (1) |
ropt (2) |
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| N(1)C(2) |
1.3328 |
1.3309 |
| C(2)C(3) |
1.3982
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1.3960
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C(3)C(4)
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1.3952
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1.3931
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| C(4)C(5) |
1.3865
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1.3841
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| C(5)C(6) |
1.3942
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1.3920
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| C(6)N(1) |
1.3359 |
1.3339 |
| C(6)NC(2) |
117.21 |
117.19 |
| NC(2)C(3) |
123.43 |
123.43 |
| C(2)C(3)C(4) |
118.52 |
118.56 |
| C(3)C(4)C(5) |
118.52 |
118.46 |
| C(4)C(5)C(6) |
118.32 |
118.37 |
| C(5)C(6)N |
123.99 |
123.98 |
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C(3)C
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1.4805
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1.4792
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C=O
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1.2123
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1.2077
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C--O
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1.3476
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1.3466
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O--H
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0.9698
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0.9679
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| trans-Nicotinic Acid |
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ropt (1) |
ropt (2) |
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| N(1)C(2) |
1.3315 |
1.3294 |
| C(2)C(3) |
1.3983
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1.3964
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| C(3)C(4) |
1.3955
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1.3933
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| C(4)C(5) |
1.3879
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1.3856
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| C(5)C(6) |
1.3935
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1.3911
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| C(6)N(1) |
1.3365 |
1.3348 |
| C(6)NC(2) |
117.07 |
117.09 |
| NC(2)C(3) |
123.64 |
123.60 |
| C(2)C(3)C(4) |
118.50 |
118.53 |
| C(3)C(4)C(5) |
118.32 |
118.32 |
| C(4)C(5)C(6) |
118.48 |
118.48 |
| C(5)C(6)N |
123.98 |
123.97 |
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C(3)C
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1.4799
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1.4788
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C=O
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1.2117
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1.2071
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C--O
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1.3496
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1.3485
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O--H
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0.9698
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0.9679
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| Table 4. Nicotinic
Acid. Rotational Constants (MHz). Normal Species. |
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ropt (1) =
B3P86/6-31G(d,p) optimization. |
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ropt (2) =
B3P86/6-31G(3d,3p) optimization. |
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cis-Nicotinic Acid |
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Calc. ropt (1) |
Calc. ropt (2) |
Expt. [1] |
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A |
3961.1 |
3974.2 |
3944.2182(12) |
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B |
1248.7 |
1252.1 |
1245.13484(35) |
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C |
949.4 |
952.1 |
947.00712(20) |
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trans-Nicotinic Acid |
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A |
3963.8 |
3977.4 |
3947.9594(11) |
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B |
1247.5 |
1250.7 |
1243.65955(32) |
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C |
948.9 |
951.5 |
946.40083(18) |
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[1] S.Mata, I.Peña, C.Cabezas,
J.C.López, and J.L.Alonso, J.Mol.Spectrosc. 280,91(2012).
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Pyridine |
Isonicotinic Acid
| Picolinic Acid
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Pyridine-3-Carbaldehyde
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Table of Contents |
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Molecules/Nitrogen |
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nicotinic_acid.html |
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Last
Modified 21 August 2012 |
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