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Amavadin and Homologues as Mediators of Water Oxidation
Author(s) -
Domarus Magdalena,
Kuznetsov Maxim L.,
Marçalo Joaquim,
Pombeiro Armando J. L.,
da Silva José Armando L.
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201509604
Subject(s) - chemistry , moiety , vanadium , redox , oxidation state , metal , stereochemistry , mass spectrometry , transition metal , medicinal chemistry , reaction mechanism , photochemistry , crystallography , inorganic chemistry , catalysis , organic chemistry , chromatography
The vanadium(IV) N‐hydroxyiminodicarboxylate complexes [V(HIDPA) 2 ] 2− and [V(HIDA) 2 ] 2− , close models of the amavadin (a natural product from Amanita fungi lacking the V=O group but exhibiting a rare NO‐bound oxyiminate moiety), are shown to be the first recognized complexes of the early transition metals (up to periodic Group 7) that mediate the oxidation of water. The reactions were analyzed by visible spectrophotometry, mass spectrometry, and measurement of evolved dioxygen using Ce 4+ as sacrificial oxidant. A mechanism proposed on the basis of DFT calculations involves the reversible oxidation to the mononuclear V V ‐{ON˙<} center, where the redox active oxyimino group plays a key role and metal oxidation state variation is only one unit. The more similar model of the metallobiomolecule, [V(HIDPA) 2 ] 2− , displays a lower oxidation rate than [V(HIDA) 2 ] 2− but does not undergo appreciable degradation, in contrast to the latter.