Preparation and Characterization of a Bis-Semiquinone: a Bidentate Dianion Biradical

Untitled

“…Bearing this in mind, we have synthesized a 1,10-phenanthroline-cobalt adduct (Scheme 1) of the dioxolene ligand 3,5-bis(3A,4A-dihydroxy-5A-tert-butylphenyl)-1-tert-butylbenzene (L) 10 which according to its geometry may act as bisbidentate ligand towards two different metal ions. Once coordinated this ligand may give by one-electron oxidation the trinegative radical anion we indicate as Sq-Cat, which, although not physically characterized, can be expected to behave as a class II mixed valence radical ligand.…”

Nickel(ii) Complexes With ‘Non Innocent’ Ligands – Cycloaminomethyl Derivatives of 1,2-Dihydroxybenzene: Sod-Like and Antimicrobial Activity

“…Based on the spectroscopic features of the complexes and some previous results [19], the planar square polyhedra of low-spin complexes Ni(L I )2-Ni(L V )2 are found to be formed by Ni(II) ions and the ligands in the monoanionic form. The ESR spectra of these compounds displayed no singlet signals (g=2.004-2.006, H<7) specific for phenoxyl radicals [20], which indicates that the ligands HL I -HL V do not undergo oxidation in the coordinated state upon crystallization. The plausible coordination mode of the Ni(II) complexes with HL I -HL V is presented in Fig.1.…”

Structure-Property Relationships in New Semiquinone-Type Ligands: Past, Present, and Future Research Efforts

“…Our design is schematized below and features cross-conjugated, [24] electroactive molecules. Recently, we have focused on quinone-containing species, [40][41][42][43][44][45][46][47][48][49] although we have reported porphyrin-containing molecules. [50][51][52][53][54] The Electroactive Groups (EG) can be either oxidized or reduced by one or more electrons to produce paramagnetic functionalities.…”

“…Bis(semiquinone)s 1 -5 [40][41][42][43][44][45][46][47][48][49] will be used to test how conformation affects the Linker's ability to exchange couple two semiquinones. Likewise, one-electron reduction of metal complexes of 1 -5 will yield Downloaded by [The University of Manchester Library] at 08:43 09 December 2014 mixed-valent semiquinone-Linker-catecholate complexes, and we can test how conformation modulates delocalization.…”