| Περίληψη: | The effect of peri-fusion on the aromaticity of 6-membered N−, O−, N,N−, N,N,N− and N,O-doped naphthalene derivatives has been studied via NICS-z, -xz, -xy, and -xyz scans employing DFT and MP2 calculations. The relative aromaticity of these structures was found to vary with the type of heteroring and the distance from the plane. Their corresponding ordering depends on the scan approaches. Accordingly, i) along the z axis at the center of the naphthalene B and C constituent rings, it is 1,8>2>7,9≫4>6, 5>3 (the most aromatic members are naphthalene and the N,O-derivative 8), ii) along the x symmetry axis of naphthalene, it is 3>8,7>5>4>9>6>2>1 (the most aromatic one is a N-derivative 3) and iii) along the z axis, on the xy plane, it is 6>1>8>9>2>5>7>3>4 at z=0.8 Å and 1>2>8>9>6>7>5>3>4 at 2.4 Å (the most aromatic ones are the N,N,N-derivative 6 at 0.8 Å and naphthalene at 2.4 Å). Their relative magnetic anisotropy ordering remains virtually unaltered in all different approaches (z-, xz-, xy-, and xyz-scans), as does their aromaticity at z=2.4 Å. The σ component of the total density is dominant close to the plane while the π component picks up in significance with increasing distance from the plane. The peri-fused ring appears to be a heteroring not just a heterobridge. |
