Formation of Ni(ii)-phenoxyl radical complexes by O2: a mechanistic insight into the reaction of Ni(ii)-phenol complexes with O2

Takashi Suzuki; Akari Sato; Hiromi Oshita; Tatsuo Yajima; Fumito Tani; Hitoshi Abe; Kaoru Mieda-Higa; Sachiko Yanagisawa; Takashi Ogura; Yuichi Shimazaki

doi:10.1039/d1dt00105a

Formation of Ni(ii)-phenoxyl radical complexes by O₂: a mechanistic insight into the reaction of Ni(ii)-phenol complexes with O₂

Takashi Suzuki, Akari Sato, Hiromi Oshita, Tatsuo Yajima, Fumito Tani, Hitoshi Abe, Kaoru Mieda-Higa, Sachiko Yanagisawa, Takashi Ogura, Yuichi Shimazaki

Department of Applied Molecular Chemistry

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2 Citations (Scopus)

Abstract

A reaction of Ni(ClO₄)₂·6H₂O with a tripodal ligand having two di(tert-butyl)phenol moieties, H₂tbuL, and 1 equivalent of triethylamine in CH₂Cl₂/CH₃OH (1 : 1, v/v) under N₂gave a Ni^II-(phenol)(phenolate) complex, [Ni(HtbuL)(CH₃OH)₂]ClO₄. The formation of the Ni^II-phenoxyl radical complex by O₂was observed in the reaction of this complex in the solid state. On the other hand, the Ni^II-phenoxyl radical complex [Ni(Me₂NL)(CH₃OH)₂]ClO₄was obtained by the reaction of H₂Me₂NL having ap-(dimethylamino)phenol moiety with Ni(ClO₄)₂·6H₂O in a similar procedure under O₂, through the oxidation of the Ni^II-(phenol)(phenolate) complex. However, a direct redox reaction of the Ni^IIion could not be detected in the phenoxyl radical formation. The results of the reaction kinetics, XAS and X-ray structure analyses suggested that the O₂oxidation from the Ni^II-(phenol)(phenolate) complex to the Ni^II-phenoxyl radical complex occursviathe proton transfer-electron transfer (PT-ET) type mechanism of the phenol moiety weakly coordinated to the nickel ion.

Original language	English
Pages (from-to)	5161-5170
Number of pages	10
Journal	Dalton Transactions
Volume	50
Issue number	15
DOIs	https://doi.org/10.1039/d1dt00105a
Publication status	Published - Apr 21 2021

All Science Journal Classification (ASJC) codes

Inorganic Chemistry

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10.1039/d1dt00105a

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@article{101dd262a3cb48c18369c40d9301ab02,

title = "Formation of Ni(ii)-phenoxyl radical complexes by O2: a mechanistic insight into the reaction of Ni(ii)-phenol complexes with O2",

abstract = "A reaction of Ni(ClO4)2·6H2O with a tripodal ligand having two di(tert-butyl)phenol moieties, H2tbuL, and 1 equivalent of triethylamine in CH2Cl2/CH3OH (1 : 1, v/v) under N2gave a NiII-(phenol)(phenolate) complex, [Ni(HtbuL)(CH3OH)2]ClO4. The formation of the NiII-phenoxyl radical complex by O2was observed in the reaction of this complex in the solid state. On the other hand, the NiII-phenoxyl radical complex [Ni(Me2NL)(CH3OH)2]ClO4was obtained by the reaction of H2Me2NL having ap-(dimethylamino)phenol moiety with Ni(ClO4)2·6H2O in a similar procedure under O2, through the oxidation of the NiII-(phenol)(phenolate) complex. However, a direct redox reaction of the NiIIion could not be detected in the phenoxyl radical formation. The results of the reaction kinetics, XAS and X-ray structure analyses suggested that the O2oxidation from the NiII-(phenol)(phenolate) complex to the NiII-phenoxyl radical complex occursviathe proton transfer-electron transfer (PT-ET) type mechanism of the phenol moiety weakly coordinated to the nickel ion.",

author = "Takashi Suzuki and Akari Sato and Hiromi Oshita and Tatsuo Yajima and Fumito Tani and Hitoshi Abe and Kaoru Mieda-Higa and Sachiko Yanagisawa and Takashi Ogura and Yuichi Shimazaki",

note = "Publisher Copyright: {\textcopyright} The Royal Society of Chemistry 2021.",

year = "2021",

month = apr,

day = "21",

doi = "10.1039/d1dt00105a",

language = "English",

volume = "50",

pages = "5161--5170",

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TY - JOUR

T1 - Formation of Ni(ii)-phenoxyl radical complexes by O2

T2 - a mechanistic insight into the reaction of Ni(ii)-phenol complexes with O2

AU - Suzuki, Takashi

AU - Sato, Akari

AU - Oshita, Hiromi

AU - Yajima, Tatsuo

AU - Tani, Fumito

AU - Abe, Hitoshi

AU - Mieda-Higa, Kaoru

AU - Yanagisawa, Sachiko

AU - Ogura, Takashi

AU - Shimazaki, Yuichi

PY - 2021/4/21

Y1 - 2021/4/21

N2 - A reaction of Ni(ClO4)2·6H2O with a tripodal ligand having two di(tert-butyl)phenol moieties, H2tbuL, and 1 equivalent of triethylamine in CH2Cl2/CH3OH (1 : 1, v/v) under N2gave a NiII-(phenol)(phenolate) complex, [Ni(HtbuL)(CH3OH)2]ClO4. The formation of the NiII-phenoxyl radical complex by O2was observed in the reaction of this complex in the solid state. On the other hand, the NiII-phenoxyl radical complex [Ni(Me2NL)(CH3OH)2]ClO4was obtained by the reaction of H2Me2NL having ap-(dimethylamino)phenol moiety with Ni(ClO4)2·6H2O in a similar procedure under O2, through the oxidation of the NiII-(phenol)(phenolate) complex. However, a direct redox reaction of the NiIIion could not be detected in the phenoxyl radical formation. The results of the reaction kinetics, XAS and X-ray structure analyses suggested that the O2oxidation from the NiII-(phenol)(phenolate) complex to the NiII-phenoxyl radical complex occursviathe proton transfer-electron transfer (PT-ET) type mechanism of the phenol moiety weakly coordinated to the nickel ion.

AB - A reaction of Ni(ClO4)2·6H2O with a tripodal ligand having two di(tert-butyl)phenol moieties, H2tbuL, and 1 equivalent of triethylamine in CH2Cl2/CH3OH (1 : 1, v/v) under N2gave a NiII-(phenol)(phenolate) complex, [Ni(HtbuL)(CH3OH)2]ClO4. The formation of the NiII-phenoxyl radical complex by O2was observed in the reaction of this complex in the solid state. On the other hand, the NiII-phenoxyl radical complex [Ni(Me2NL)(CH3OH)2]ClO4was obtained by the reaction of H2Me2NL having ap-(dimethylamino)phenol moiety with Ni(ClO4)2·6H2O in a similar procedure under O2, through the oxidation of the NiII-(phenol)(phenolate) complex. However, a direct redox reaction of the NiIIion could not be detected in the phenoxyl radical formation. The results of the reaction kinetics, XAS and X-ray structure analyses suggested that the O2oxidation from the NiII-(phenol)(phenolate) complex to the NiII-phenoxyl radical complex occursviathe proton transfer-electron transfer (PT-ET) type mechanism of the phenol moiety weakly coordinated to the nickel ion.

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SN - 1477-9226

VL - 50

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EP - 5170

JO - Dalton Transactions

JF - Dalton Transactions

IS - 15

ER -

Formation of Ni(ii)-phenoxyl radical complexes by O₂: a mechanistic insight into the reaction of Ni(ii)-phenol complexes with O₂

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