In‐Plane‐Bishomoaromatizität in Tetrastickstoff‐Dianionen: molekulare und elektronische Strukturen

Abstract

Na4N8‐Kuboktaeder mit nahezu planaren N4‐Polygonen (siehe Struktur) bilden im Festkörper wie auch in Lösung die Kerne der Dimerstrukturen bemerkenswert persistenter bishomoaromatischer Dianionen, die durch Reduktion von vororientierten Bisdiazenen mit Natrium erzeugt wurden. Hinsichtlich der transannularen N‐N‐Wechselwirkungen (dN‐N=2.5–2.8 Å) weisen quantenchemische Rechnungen lange Bindungen aus.

Towards In‐Plane Delocalized 4N/7e Radical Cations and 4N/6e Dications – One‐/Two‐Electron Oxidation of Proximate‐Parallel Bis(N,N'‐bicyclic)‐bishydrazines

“…[6] The very recently determined crystal structures of Na 4 B 2 aggregates, in good agreement with the calculations, visualize perfect in-plane delocalization. [52] The attempts to further improve our prior work, particularly the activities directed towards the tetraazacages 1-3 and the derived C-type 4N/ 7(6)e cations, were not nearly as rewarding. Thus, even the seemingly most promising of the synthetic routes abstracted in Scheme 1 (G Ǟ H Ǟ I) came to an early end [16 (21) Ǟ 17].…”

“…After stirring for 30 min, keeping at room temperature for 2 h (single product, TLC), and concentration in vacuo, the solid, uniform (TLC) residue was filtered and washed thoroughly with CHCl 3 , J 10,17a = 4.5, J 10,17s = 1.9, J 13,18a = 4.6, J 13,18s = 1.5, J 15a,15s = 14.3, J 15s,16a = 6.8, J 15s,16s = 10.5, J 16a,16s = 13.5, J 15a,16s = 3.0, J 15a,16a = 9.8, J 17a,17s = 14.3, J 17a,18s = 5.3, J 17a,18a = 11.3, J 17s,18s = 11.3, J 17s,18a = 10.5, J 18a,18s = 13.5 Hz. 13 C NMR: δ = 154.6 (C-3*), 154.1 (C-6*), 134.0 (C-4,-5), 67.9 (C-10**), 63.9 (C-13**), 52.0 (C-1***), 51.8 (C-8***), 48.7 (C-14), 42.5 (C-9), 24. …”

(π+σ)‐double aromatic and π,σ‐mixed aromatic boron compounds with two electrons delocalized over three centers

“…These will be described in the second part of this review. The homo ( + )-double aromatics reviewed in this paper as well as a recently characterized in-plane -bishomoaromatic [14] do not belong to Winstein type homoaromatics. The aromatics presented may be classified according to the orientation of the axes [15] of the atomic orbitals forming the molecular orbital of the cyclically delocalized electrons, with respect to the plane of the centers of this delocalization (Scheme 2).…”