|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
C4N2H2F2
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nitrogen
|
|
|
Nuclear
Quadrupole Coupling Constants |
|
|
|
in 2,6-Difluoropyrazine |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The molecular structure of fluoropyrazine was
optimized at the B3P86/ 6-31G(3d,3p) level of theory. C2V
symmetry was assumed. On this structure, calculation was made
of the nitrogen nqcc's. These are given in Table 1. Structure
parameters are given in Table 2, atomic coordinates in Table 3,
and rotational constants in Table 4. |
|
|
|
|
|
|
|
|
|
|
|
|
In Table 1, 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 2,6-Difluoropyrazine (MHz). Calculation
was made on the B3P86/6-31G(3d,3p) ropt structure. |
|
| |
|
|
|
|
|
|
|
|
|
|
|
Calc. |
|
Expt. |
|
| |
|
|
|
|
|
|
|
|
14N(2) |
Xaa |
|
1.652 |
|
|
|
|
|
Xbb |
- |
4.276 |
|
|
|
|
|
Xcc |
|
2.624 |
|
|
|
|
|
ETA * |
|
0.227 |
|
|
|
|
|
|
|
|
|
|
|
|
|
RSD |
|
0.030 (1.3 %) |
|
|
|
|
|
|
|
|
|
|
|
|
14N(6) |
Xaa |
|
1.253 |
|
|
|
|
|
Xbb |
- |
5.369 |
|
|
|
|
|
Xcc |
|
4.116 |
|
|
|
|
|
ETA * |
|
0.533 |
|
|
|
|
|
|
|
|
|
|
|
|
|
RSD |
|
0.030 (1.3 %) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
* ETA = (Xaa - Xcc)/Xbb
= (Xxx - Xyy)/Xzz. |
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
| Table 2. 2,6-Difluoropyrazine. Molecular structure parameters, ropt (Å
and degrees). |
| |
|
|
|
|
|
|
|
N(1)C(2) |
1.3128 |
|
|
|
C(2)C(3) |
1.3910 |
|
|
|
C(3)N(4) |
1.3288 |
|
|
|
C(2)F(2) |
1.3263 |
|
|
|
C(3)H(3) |
1.0843 |
|
|
|
C(6)N(1)C(2) |
114.80 |
|
|
|
N(1)C(2)C(3) |
123.91 |
|
|
|
C(2)C(3)N(4) |
119.79 |
|
|
|
C(3)N(4)C(5) |
117.80 |
|
|
|
N(1)C(2)F(2) |
116.55 |
|
|
|
C(2)C(3)H(3) |
121.32 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Table 3. 2,6-Difluoropyrazine. Atomic coordinates, ropt. |
| |
|
|
|
|
|
|
|
|
a (Å) |
|
b (Å) |
|
|
|
|
|
|
|
N(1) |
|
0.0 |
- |
0.9711 |
|
C(2,6) |
± |
1.1060 |
- |
0.2638 |
|
C(3,5) |
± |
1.1378 |
|
1.1268 |
|
N(4) |
|
0.0 |
|
1.8132 |
|
F(2,6) |
± |
2.2447 |
- |
0.9439 |
|
H(3,5) |
± |
2.0767 |
|
1.6692 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Table 4. 2,6-Difluoropyrazine. Rotational Constants
(MHz). |
| |
|
|
|
|
|
Calc ropt |
Expt. |
|
|
|
|
|
A |
3862.1 |
|
|
B |
1939.5 |
|
|
C |
1291.1 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Pyrazine |
Pyridine |
|
|
Pyrimidine |
1,3,5-Triazine |
|
Chloropyrazine |
2-Fluoropyridine |
|
2,3-Difluoropyrazine |
3-Fluoropyridine |
|
Fluoropyrizine |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Table of Contents
|
|
|
|
|
|
|
Molecules/Nitrogen |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
26DFPyrazine.html |
|
|
|
|
|
|
Last
Modified 21 Feb 2004 |
|
|
|
|
|
|
|
|
|
|