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Crystallography 2018 Structural Chemistry & Crystallography Communication
ISSN: 2470-9905 Page 29
June 04-05, 2018
London, UK
3rd Edition of International Conference on
Advanced Spectroscopy,
Crystallography and Applications
in Modern Chemistry
Oxidation chemistry of redox active transition metal
complexes with pro-radical ligands and their detailed
electronic structures have been actively pursued in recent
years. An “experimental” valence state of metal complexes is
sometime different from the “formal” oxidation state, especially
in the species having redox active ligands. This difference can
be seen in biological system, such as iron(IV)-porphyrin -cation
radical in some heme proteins and copper(II)-phenoxyl radical
in galactose oxidase (GO). Many efforts for determination of the
experimental oxidation number have been close to the goal of
the “truth oxidation state” in various oxidized metal complexes
with redox-active ligands. Depending on the relative energies of
the redox-active orbitals, metal complexes with non-innocent
ligands exist in two limiting descriptions, either a metal-
ligand radical (Mn+(L•)) or a high valent metal (M(n+1)+(L))
complex. The reaction mechanisms of artificial and biological
catalysts depend on the electronic structures of the high
valent intermediates. However, structural characterizations
of these species by X-ray diffraction methods have been rare
due to their stability. Recently, some artificial metal−phenoxyl
radical complexes as models of GO have been synthesized and
successfully characterized by X-ray crystal structure. The one-
electron oxidized metal-phenolate complexes showed various
electronic structures depending on small perturbations, such
as substitution of the phenolate ring and the chelate effect
of the phenolate ligands and so on. In this presentation, I will
focus on X-ray crystal structures of the one- and two-electron
oxidized metal(II)–phenolate complexes (Ni(II), Pd(II), Pt(II)
and Cu(II)) with Schiff base ligands of 2N2O donor sets.
Especially electronic and crystal structure relationship such
as differences of metal-phenoxyl radical and high-valent metal
phenolate complexes, and the effect of different oxidation
locus of the radical electron on the ligands in oxidized forms
will be discussed.
Recent Publications
1. Oshita H, Shimazaki Y, Yamauchi O, et al.
Characterization of the one-electron oxidized Cu(II)-
salen complexes with a side chain aromatic ring: The
effect of the indole ring on the Cu(II)-phenoxyl radical
species. J. Bio. Inorg. Chem., in press.
2. Oshita H, Shimazaki Y, Group 10-Metal-p-
Substituted Phenoxyl Radical Complexes with Schiff
Base Ligands. ChemSelect., in press.
3. Shimazaki Y, Yajima T, Yamauchi O. (2015) Properties
of the indole ring in metal complexes. A comparison
with the phenol ring. J. Inorg. BioChem, 148: 105-115.
Biography
Yuichi Shimazaki was born in 1970 in Toyama prefecture, Japan. He re-
ceived his Doctor’s degree in science from Nagoya University in 2000 under
the supervision of Professor Osamu Yamauchi. He joined Professor Yoshi-
nori Naruta’s group at Kyushu University as Assistant Professor and worked
on the redox behavior of various metal porphyrin complexes as models of
the active site of metalloenzymes. In 2008 he was promoted to Associate
Professor at the College of Science, Ibaraki University. His research inter-
ests include the oxidation chemistry of the complexes of various metal ions,
model studies of metalloenzymes, bioorganometallic chemistry, and weak
interactions in metal-organic molecule systems.
CRYSTALLOGRAPHY OF OXIDIZED METAL(II)- DI(PHENOLATE) COMPLEXES;
GEOMETRIC AND ELECTRONIC STRUCTURES RELATIONSHIP
Yuichi Shimazaki
Ibaraki University, Japan
Yuichi Shimazaki, Struct Chem Crystallogr Commun 2018, Volume 4
DOI: 10.21767/2470-9905-C1-005