Table 2.
Experimental and calculated geometric parameters of 4-nitropyridine-N-oxide.a.
| (rh1, ∠h1)b | (re, ∠e) B3LYP/aug-cc-pVTZ |
(re, ∠e) PBE0/aug-cc-pVTZ |
re, ∠e) MP2/aug-cc-pVTZ |
|
|---|---|---|---|---|
| r(N1–O1) | 1.267(3) p1c | 1.264 | 1.252 | 1.259 |
| r(N2–O2) | 1.227(3) (p1) | 1.224 | 1.214 | 1.232 |
| r(N1–C3) | 1.373(4) p2 | 1.373 | 1.367 | 1.380 |
| r(N2–C1) | 1.460(4) (p2) | 1.460 | 1.452 | 1.453 |
| r(C2–C3) | 1.378(4) p3 | 1.372 | 1.369 | 1.374 |
| r(C1–C2) | 1.395(4) (p3) | 1.389 | 1.385 | 1.391 |
| r(C2–H1) | 1.094(8) p4 | 1.079 | 1.081 | 1.080 |
| r(C3–H4) | 1.092(8) (p4) | 1.077 | 1.079 | 1.079 |
| ∠ C3N1C4 | 118.6(9) p5 | 118.9 | 118.8 | 118.5 |
| ∠ N1C3C2 | 121.8(6) p6 | 121.3 | 121.5 | 121.5 |
| ∠ C3C2C1 | 118.8(9) | 119.3 | 119.2 | 119.1 |
| ∠ C2C1C5 | 120.1(9) | 119.9 | 119.9 | 120.1 |
| ∠ C1N2O2 | 117.8(6)p7 | 117.5 | 117.4 | 117.4 |
a
Distances in Å and angles in degrees. For atom numbering see Fig. 1.
b
Uncertainties in rh1 σ=(σsc2+(2.5σLS)2)1/2 (σsc = 0,002r, σLS–standard deviation in least-squares refinement), for angles σ = 3σLS.
c
pi – parameter refined independently. (pi) – parameters calculated from the independent parameter pi by a difference Δ = pi-(pi) from the quantum chemical calculations (B3LYP/aug-cc-pVTZ).