The Chemistry of Formazans and Tetrazolium Salts

Nineham, A. W.

doi:10.1021/cr50002a004

Cited by 290 publications

(193 citation statements)

References 73 publications

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“…The hydrochloride adopts a closed-ring syn,s-cis structure (6) and provides the first crystallographic evidence for this configuration in an uncoordinated formazan. Confirmation of the postulated syn,s-cis structure for the series of red formazans in general was sought in the present study of the title compound [(3); Ar = 2,6-dimethylphenyl, R = NO 2] (Nineham, 1955;Hooper, 1969;Hutton, 1980). …”

Section: X-ray Crystallographic Investigations Of Formazansmentioning

confidence: 97%

The structure of 1,5-bis(2,6-dimethylphenyl)-3-nitroformazan

Dijkstra¹,

Hutton²,

Irving³

et al. 1982

Acta Crystallogr Sect B

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Section: X-ray Crystallographic Investigations Of Formazansmentioning

confidence: 97%

The structure of 1,5-bis(2,6-dimethylphenyl)-3-nitroformazan

Dijkstra¹,

Hutton²,

Irving³

et al. 1982

Acta Crystallogr Sect B

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“…25,26 In the present study, formazans (4a-4h) were synthesized according to the first method reported by Nineham,27 namely the coupling of substituted phenylhydrazones with 4-bromoaniline diazonium cation (3) in basic media at 0 • C as demonstrated in Scheme 1. New formazans 4a-4h, recrystallized from methanol, were obtained in overall yields of 50%-75%.…”

mentioning

confidence: 99%

Experimental and computational studies on the absorption properties of novel formazan derivatives

Turkoglu¹,

Çınar²

2017

Turk J Chem

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“…[7] However, the limited stability of β-diketiminate complexes upon changing oxidation state prevents widespread application. [8] Formazanates (1,2,4,5-tetraazapentadienyls), [9] which are close analogues of β-diketiminates, have received comparatively little attention as ligands in coordination chemistry. [10] The stability of organic 6-membered heterocyclic radicals (verdazyls) that are derived from formazans prompted us to explore the use of formazanates as potential redox-active ligands (Chart 1).…”

mentioning

confidence: 99%

The Formazanate Ligand as an Electron Reservoir: Bis(Formazanate) Zinc Complexes Isolated in Three Redox States

et al. 2014

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Metal-mediated redox processes are of fundamental importance in a wide variety of bond formation and cleavage reactions. The utility of transition metal catalysts in this type of reactions stems from their ability to switch between two (or more) oxidation states. Recently, there has been increased interest in redox processes that do not occur at the metal centre, but instead take place within the ancillary ligand framework (so-called 'redox-active' or 'non-innocent' ligands). [1] The use of organic ligands as redox equivalents is of key importance in biological (enzymatic) transformations, [2] and has been shown to open new reactivity pathways in catalysis. [1c] The most studied ligands of this class are dithiolenes and dioxolenes, while recent work has focussed on α-diimines [3] and bis(imino)pyridines. [4] A class of ligands that has found widespread utility in the synthesis of metal complexes across the periodic table are the monoanionic β-diketiminates. [5] These are generally considered as stable ligand scaffolds without involvement in redox-chemistry. Recently, examples of β-diketiminate metal complexes were reported in which the ligand was either reduced to a metal-bound di-or trianion, [6] or oxidized to a neutral radical species. [7] However, the limited stability of β-diketiminate complexes upon changing oxidation state prevents widespread application. [8] Formazanates (1,2,4,5-tetraazapentadienyls), [9] which are close analogues of β-diketiminates, have received comparatively little attention as ligands in coordination chemistry. [10] The stability of organic 6-membered heterocyclic radicals (verdazyls) that are derived from formazans prompted us to explore the use of formazanates as potential redox-active ligands (Chart 1). Here we show that zinc complexes with formazanate ligands engage in remarkably facile and reversible redox-chemistry which allows the full characterization of bis(formazanate) L 2 Zn complexes in charge neutral, anionic or dianionic redox states.

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The Chemistry of Formazans and Tetrazolium Salts

Cited by 290 publications

References 73 publications

The structure of 1,5-bis(2,6-dimethylphenyl)-3-nitroformazan

The structure of 1,5-bis(2,6-dimethylphenyl)-3-nitroformazan

Experimental and computational studies on the absorption properties of novel formazan derivatives

The Formazanate Ligand as an Electron Reservoir: Bis(Formazanate) Zinc Complexes Isolated in Three Redox States

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