Reversible Solution π‐Dimerization and Long Multicenter Bonding in a Stable Phenoxyl Radical

Abstract

Reversible solution π-dimerization is observed in the stable neutral phenoxyl radical 2,6-bis-(8-quinolylamino)-4-(tert-butyl)phenoxyl baqp and is spectroscopically characterized. This behavior, not previously observed for π-extended phenoxyl radicals, is relevant to the formation of long multicenter bonding in the π-dimer at low temperature akin to previously reported phenalenyl radicals. Our experimental data are supported in a quantitative manner by results from density functional theory (DFT) and ab initio molecular orbital theory calculations. Our theoretical results indicate that the solution dimer features strong bonding interactions between the two phenoxyl rings but that the stability of the dimer is also related to dispersion interactions between the flanking nearly parallel quinolyl rings.

A Building Information Modelling approach to the alignment of organisational objectives to Asset Information Requirements

“…Information requirements do not arise naturally and therefore have to be engineered, highlighting the need for improving techniques in the development of information requirements to meet this significant challenge [18].…”

Magnetic Properties of π-Conjugated Hybrid Phenoxyl–Nitroxide Radicals with Extended π-Spin Delocalization

“…Importantly, the stability of phenoxyl−nitroxides arises from both the steric hindrance induced by bulky tert-butyl groups near the phenoxyl site and the efficient delocalization of the unpaired electron over the molecular frame. 30 It should be noted that the union of a sterically hindered phenol with the strong acceptor 4H-imidazole 3-oxide moiety gives sufficient stabilization for the hybrid paramagnetic molecule, while the presence of other heterocyclic substituents at the C-4 of the phenol ring does not lead to significant radical stabilization. 31 It is essential that the presence of the tert-butyl groups changes the geometry of the hybrid radicals, making them nonplanar which influences their crystal packing mode and destroys the symmetry of the head-over-tail π−π-dimers typically formed by flat conjugated compounds in the crystalline state.…”

“…Importantly, the stability of phenoxyl–nitroxides arises from both the steric hindrance induced by bulky tert -butyl groups near the phenoxyl site and the efficient delocalization of the unpaired electron over the molecular frame . It should be noted that the union of a sterically hindered phenol with the strong acceptor 4 H -imidazole 3-oxide moiety gives sufficient stabilization for the hybrid paramagnetic molecule, while the presence of other heterocyclic substituents at the C-4 of the phenol ring does not lead to significant radical stabilization .…”

A Neutral Fe4tBuL4 All Ferric Grid Complex: Structural and Variable Temperature Magnetic Properties

“…Other fascinating Fe 4 grid complexes have since been reported with interesting magnetic profiles and metal‐centered redox activity; however, there are to the best of our knowledge no examples of Fe 4 grid complexes where the redox behaviour of the ligand plays a role in the switching properties. As our initial foray into the synthesis of self‐assembled [2×2] grid complexes with ligand centered redox properties, herein we describe the structure and variable temperature magnetic properties of an Fe 4 grid complex containing a ditopic redox‐active ligand 2,6‐ bis( 8‐quinolylamino)‐4‐( tert ‐butyl)phenol ( t Bu H 3 L , Figure ) , …”