|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
4-CH3-C5H4N
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nitrogen
|
|
|
Nuclear
Quadrupole Coupling Constants |
|
|
|
in 4-Methylpyridine |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nitrogen nqcc's in 4-methylpyridine
were calculated here on molecular structures given by B3P86/6-31G(3d,3p)
optimization assuming Cs symmetry with the plane of symmetry ( I ) perpendicular
to and ( II ) coincident with the plane of the pyridine ring. These calculated nqcc's
are compared with the experimental nqcc's of Dreizler et al. [1] in Tables
1 and 2. Structure parameters are given in Table 3, atomic coordinates
in Table 4, rotational constants in Table 5.
|
|
|
|
|
|
|
|
|
|
|
|
|
In Table 1, subscripts a,b,c
refer to the principal axes of the inertia tensor, subscripts 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.
|
|
|
RMS is the root mean square
differene between calculated and experimental nqcc's (percent of
average experimental nqcc). RSD
is the calibration residual standard deviation of the
B3PW91/6-311+G(df,pd) model for
calculation of the nqcc's. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
Table 1. Nitrogen nqcc's in 4-Methylpyridine, conformer I (MHz). Calculation
was made on the B3P86/6-31G(3d,3p) ropt structure. |
|
|
|
|
|
|
|
|
|
|
|
|
|
Calc. |
|
Expt. |
|
| |
|
|
|
|
|
|
|
|
14N |
Xaa |
- |
4.783 |
- |
4.82(4) |
|
|
|
Xbb |
|
1.475 |
|
1.04 |
|
|
|
Xcc |
|
3.308 |
|
3.78 |
|
|
|
|Xab| |
|
0.026 |
|
|
|
|
|
|
|
|
|
|
|
|
|
RMS |
|
0.37 (11.6 %) |
|
|
|
|
|
RSD |
|
0.030 (1.3 %) |
|
|
|
|
|
|
|
|
|
|
|
|
|
Xxx |
|
1.475 |
|
|
|
|
|
Xyy |
|
3.308 |
|
|
|
|
|
Xzz |
- |
4.783 |
|
|
|
|
|
ETA |
|
0.383 |
|
|
|
|
|
Øz,a |
|
0.19 |
|
|
|
|
|
Øa,bi |
|
0.42 |
|
|
|
|
|
Øz,bi * |
|
0.24 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
* The z-axis makes an angle of 0.24o
with the external bisector ( 'bi' ) of the C(6)N(1)C(2). |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
Table 2. Nitrogen nqcc's in 4-Methylpyridine, conformer II (MHz). Calculation
was made on the B3P86/6-31G(3d,3p) ropt structure. |
|
|
|
|
|
|
|
|
|
|
|
|
|
Calc. |
|
Expt. |
|
| |
|
|
|
|
|
|
|
|
14N |
Xaa |
- |
4.783 |
- |
4.82(4) |
|
|
|
Xbb |
|
1.475 |
|
1.04 |
|
|
|
Xcc |
|
3.308 |
|
3.78 |
|
|
|
|Xab| |
|
0.028 |
|
|
|
|
|
|
|
|
|
|
|
|
|
RMS |
|
0.37 (11.5 %) |
|
|
|
|
|
RSD |
|
0.030 (1.3 %) |
|
|
|
|
|
|
|
|
|
|
|
|
|
Xxx |
|
1.475 |
|
|
|
|
|
Xyy |
|
3.308 |
|
|
|
|
|
Xzz |
- |
4.783 |
|
|
|
|
|
ETA |
|
0.383 |
|
|
|
|
|
Øz,a |
|
0.25 |
|
|
|
|
|
Øa,bi |
|
0.15 |
|
|
|
|
|
Øz,bi * |
|
0.10 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
* The z-axis makes an angle of 0.10o
with the external bisector ( 'bi' ) of the C(6)N(1)C(2). |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Molecular energy EI < EII
by 0.016 kcal/mol calculated at the B3P86/ 6-31G(3d,3p) level of theory,
and 0.023 kcal/mol at the B3PW91/ 6-311+G(df,pd) level. |
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
| Table 3. 4-Methylpyridine and Pyridine. Molecular structure parameters, ropt (Å
and degrees). |
| |
|
|
|
|
|
|
|
|
ropt ( I )
|
ropt ( II ) |
Pyridine |
|
|
|
|
|
|
|
|
N(1)C(2) |
1.3334 |
1.3345 |
1.3336 |
|
|
C(2)C(3) |
1.3887 |
1.3877 |
1.3904 |
|
|
C(3)C(4) |
1.3973 |
1.3948 |
1.3885 |
|
|
C(4)C(5) |
1.3973 |
1.3925 |
1.3885 |
|
|
C(5)C(6) |
1.3887 |
1.3898 |
1.3904 |
|
|
C(6)N(1) |
1.3334 |
1.3324 |
1.3336 |
|
|
C(2)H(2) |
1.0881 |
1.0881 |
1.0880 |
|
|
C(3)H(3) |
1.0856 |
1.0857 |
1.0845 |
|
|
C(5)H(5) |
1.0856 |
1.0855 |
1.0845 |
|
|
C(6)H(6) |
1.0881 |
1.0882 |
1.0880 |
|
|
C(6)N(1)C(2) |
116.43 |
116.43 |
117.03 |
|
|
N(1)C(2)C(3) |
123.98 |
124.00 |
123.80 |
|
|
C(2)C(3)C(4) |
119.44 |
119.42 |
118.44 |
|
|
C(3)C(4)C(5) |
116.74 |
116.73 |
118.50 |
|
|
C(4)C(5)C(6) |
119.44 |
119.47 |
118.44 |
|
|
C(5)C(6)N(1) |
123.98 |
123.96 |
123.80 |
|
|
N(1)C(2)H(2) |
115.96 |
115.94 |
115.94 |
|
|
C(2)C(3)H(3) |
119.95 |
119.90 |
120.21 |
|
|
C(6)C(5)H(5) |
119.95 |
119.98 |
120.21 |
|
|
N(1)C(6)H(6) |
115.96 |
115.98 |
115.94 |
|
|
|
|
|
|
|
|
C(4)C(7) |
1.4996 |
1.4999 |
|
|
|
C(7)H(8) |
1.0951 |
1.0913 |
|
|
|
C(7)H(9,10) |
1.0921 |
1.0939 |
|
|
|
C(3)C(4)C(7) |
121.63 |
121.39 |
|
|
|
C(4)C(7)H(8) |
110.60 |
111.44 |
|
|
|
C(4)C(7)H(9,10) |
111.40 |
110.98 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Table 4. 4-Methylpyridine, conformer I. Atomic coordinates, ropt. |
| |
|
|
|
|
|
|
|
|
|
|
a (Å) |
|
b (Å) |
|
c (Å) |
|
|
|
|
|
|
|
|
|
N(1) |
- |
1.8531 |
|
0 |
- |
0.0071 |
|
C(2,6) |
- |
1.1507 |
± |
1.1335 |
- |
0.0018 |
|
C(3,5) |
|
0.2369 |
± |
1.1866 |
|
0.0072 |
|
C(4) |
|
0.9678 |
|
0 |
|
0.0098 |
|
H(2,6) |
- |
1.7315 |
± |
2.0536 |
- |
0.0024 |
|
H(3,5) |
|
0.7425 |
± |
2.1473 |
|
0.0153 |
|
C(7) |
|
2.4674 |
|
0 |
- |
0.0086 |
|
H(8) |
|
2.8401 |
|
0 |
- |
1.0383 |
|
H(9,10) |
|
2.8720 |
± |
0.8862 |
|
0.4849
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Table 5. 4-Methylpyridine. Rotational Constants
(MHz). |
| |
|
|
|
|
|
ropt ( I ) |
Expt. |
|
|
|
|
|
A |
5905.9 |
|
|
B |
2539.8 |
|
|
C |
1795.8 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
[1] H.D.Rudolph, H.Dreizler,and H.Seiler, Z.Naturforsch.
22a,1738(1967). |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Pyridine |
2-Methylpyridine |
3-Methylpyridine |
|
4-Fluoropyridine |
4-Chloropyridine |
4-Bromopyridine |
|
4-Cyanopyridine |
4-Pyridine Carbaldehyde |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Table of Contents
|
|
|
|
|
|
|
Molecules/Nitrogen |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
4MePYR.html |
|
|
|
|
|
|
Last
Modified 6 Dec 2003 |
|
|
|
|
|
|
|
|
|
|