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Picolinic
Acid |
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s-cis-I Picolinic
Acid
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s-cis-II Picolinic
Acid |
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in Picolinic
Acid
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(Pyridine-2-Carboxylic
Acid) |
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Calculation of the N nqcc's in picolinic 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 efg's/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
s-cis-I Picolinic 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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0.533 |
-
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0.548 |
-
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0.5601(22) |
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Xbb |
- |
2.508 |
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2.513 |
- |
2.5718(39) |
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Xcc |
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3.041 |
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3.061 |
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3.1218(39) |
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|Xab| |
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2.736 |
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2.740 |
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RMS |
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0.061 (3.0 %) |
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0.049 (2.4 %) |
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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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1.388 |
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1.380 |
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Xyy |
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3.041 |
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3.061 |
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Xzz |
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4.429 |
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4.441 |
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ETA |
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0.373 |
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0.379 |
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Øz,a |
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54.92 |
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54.86 |
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Øa,bi * |
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55.53 |
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55.54 |
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Øz,bi |
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0.61 |
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0.68 |
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* "bi" is the bisector of the CNC
angle. |
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Table 2. 14N nqcc's in s-cis-II Picolinic 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 |
- |
0.537 |
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0.572 |
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0.5637(38) |
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Xbb |
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3.081 |
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3.066 |
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3.030(16) |
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Xcc |
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3.617 |
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3.638 |
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3.594(16) |
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|Xab| |
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3.023 |
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3.034 |
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RMS |
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0.035 (1.5 %) |
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0.033 (1.4 %) |
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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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1.471 |
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1.461 |
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Xyy |
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3.617 |
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3.638 |
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Xzz |
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5.088 |
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5.099 |
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ETA |
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0.422 |
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0.427 |
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Øz,a |
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56.41 |
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56.17 |
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Øa,bi * |
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57.25 |
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57.11 |
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Øz,bi |
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0.84 |
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0.93 |
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* "bi" is the bisector of the CNC
angle. |
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| Table 3.
Picolinic 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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| s-cis-I Picolinic
Acid |
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ropt (1) |
ropt (2) |
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| N(1)C(2) |
1.3376 |
1.3360 |
| C(2)C(3) |
1.3904 |
1.3883 |
| C(3)C(4) |
1.3898 |
1.3878 |
| C(4)C(5) |
1.3922
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1.3896
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| C(5)C(6) |
1.3930
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1.3909
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| C(6)N(1) |
1.3327
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1.3300
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C(6)N(1)C(2)
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117.94
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117.96
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| N(1)C(2)C(3) |
123.81
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123.77
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| C(2)C(3)C(4) |
117.82
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117.83
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| C(3)C(4)C(5) |
118.91
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118.91
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| C(4)C(5)C(6) |
118.84
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118.84
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| C(5)C(6)N(1) |
122.68
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122.68
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C(2)C
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1.5046
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1.5028
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C=O
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1.2078
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1.2033
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C--O
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1.3339
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1.3322
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O--H
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0.9816
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0.9801
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OH - - - N
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1.9425
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1.9450
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| s-cis-II Picolinic
Acid |
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ropt (1) |
ropt (2) |
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| N(1)C(2) |
1.3359 |
1.3344 |
| C(2)C(3) |
1.3954 |
1.3929 |
| C(3)C(4) |
1.3890 |
1.3869 |
| C(4)C(5) |
1.3906
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1.3881
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| C(5)C(6) |
1.3946
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1.3924
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| C(6)N(1) |
1.3314
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1.3288
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| C(6)N(1)C(2) |
117.11
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117.18
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| N(1)C(2)C(3)
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123.90
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123.88
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| C(2)C(3)C(4)
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118.21
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118.19
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| C(3)C(4)C(5) |
118.56
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118.57
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| C(4)C(5)C(6) |
118.55
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118.61
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| C(5)C(6)N(1) |
123.66
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123.58
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| C(2)C |
1.4951
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1.4944
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C=O |
1.2139
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1.2092
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C--O |
1.3386
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1.3372
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O--H |
0.9701
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0.9682
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Table 4. Picolinic
Acid. Rotational Constants (MHz).
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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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s-cis-I Picolinic Acid |
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Calc. ropt (1) |
Calc. ropt (2) |
Expt. [1] |
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A |
3912.6 |
3929.9 |
3903.906(16) |
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B |
1299.5 |
1301.9 |
1290.82296(17) |
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C |
975.5 |
977.9 |
970.41622(15)
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s-cis-II Picolinic Acid |
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A |
3975.5 |
3988.4 |
3958.969(17) |
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B |
1272.5 |
1276.1 |
1268.13439(16) |
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C |
964.0 |
966.8 |
961.33930(15)
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[1] I.Peña, M.Varela, V.G.Franco, J.C.López, C.Cabezas, and J.L.Alonso, J.Phys.Chem. A, 118,11373(2014).
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Pyridine |
Nicotinic Acid
| Isonicotinic Acid
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Table of Contents |
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Molecules/Nitrogen |
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picolinic_acid.html |
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Last
Modified 11 Nov 2014 |
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