N, N‐ and N, O‐6‐membered Ring peri‐Annelation in Naphthalene. Is it a Heteroring or merely a peri‐ Heterobridge?. Issue 5 (1st February 2021)

• Record Type: Journal Article
• Authors: Tzeli, Demeter; Tsoungas, Petros G.
• Is Part Of: ChemistrySelect. Volume 6:Issue 5(2021)
• Page Start: 951
• Page End: 961
• Publication Date: 2021-02-01
• Subjects: Aromaticity -- Calculations -- Naphthalene -- NICS -- N, N−, N, O-heterocyles.; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.202004237
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: 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. Abstract : Study of the effect of peri ‐fusion on the aromaticity of 6‐membered N−, O−, N, N−, N, N, N− and N, O‐doped naphthalene derivatives. Their relative aromaticity varies with respect to i) heteroatom nature of A ring, and ii) distance from the plane of the ring. The N− (N, N− and N, N, N−) structures appear to be more stable than their O−(and N, O−) doped congeners. Peri‐fusion of ring A increases the aromaticity of the structures along the x symmetry axis of naphthalene. In other words, it does, indeed, participate in the entire structure with both its σ and π components as a heteroring not as a heterobridge.