Dinuclear and mononuclear manganese(IV)-radical complexes and their catalytic catecholase activity.

Seven o-aminophenol ligands based on aniline and m-phenylenediamine, which act as mono- and di-nucleating non-innocent ligands, respectively, together with their seven Mn(IV)-complexes, 1-7 are described. One of them, 1, is dinuclear and 2-7 are mononuclear, in which the ligands are coordinated in their oxidized o-iminobenzosemiquinone radical forms. The crystal structures of 1 and 3 were determined by X-ray diffraction and the electronic structures were established by various physical methods including EPR and variable-temperature (2-290 K) susceptibility measurements. Electrochemical measurements (CV and SQW) indicate primarily ligand-centered redox processes. The Mn(IV)-radical complexes, 1-7, catalyze the oxidation of 3,5-di-tert-butylcatechol with molecular oxygen as the sole oxidant to afford 3,5-di-tert-butylquinone quantitatively under mild conditions to mimic the function of the copper-containing enzyme catechol oxidase. An "on-off" mechanism of the radicals without redox participation of the metal center is proposed for the catalytic oxidation process. Complex 1 is found to be a good catalyst for oxidative C-C coupling of hindered phenols to diphenoquinones.

[1]  J. Vittal,et al.  Syntheses, structural properties and catecholase activity of copper(II) complexes with reduced Schiff base N-(2-hydroxybenzyl)-amino acids. , 2004, Dalton transactions.

[2]  K. Wieghardt,et al.  Aerial oxidation of primary alcohols and amines catalyzed by Cu(II) complexes of 2,2'-selenobis(4,6-di-tert-butylphenol) providing [O,Se,O]-donor atoms. , 2004, Dalton transactions.

[3]  E. Bill,et al.  Non‐Oxo Vanadium(IV) Complexes of Aminebis(phenolate) [O,N,O] Donor Ligands and Solution Studies of Isostructural VIV and MnIV Complexes , 2003 .

[4]  S. Kojo,et al.  Mechanism for Aerobic Oxidation of 3,5-Di-tert-butylcatechol to 3,5-Di-tert-butyl-o-benzoquinone Catalyzed by Di-μ-hydroxo-dicopper(II) Complexes of Peralkylated Ethylelnediamine Ligands , 2003 .

[5]  J. Stubbe.  Radicals with a controlled lifestyle. , 2003, Chemical communications.

[6]  M. Giorgi,et al.  Catechol oxidase activity of dicopper complexes with N-donor ligands , 2003 .

[7]  E. Monzani,et al.  Stereoselective catalytic oxidations of biomimetic copper complexes with a chiral trinucleating ligand derived from 1,1-binaphthalene , 2003 .

[8]  K. Wieghardt,et al.  The molecular and electronic structure of [FeIII2(t-buLISQ)4(μ-O)]—a dinuclear ferric complex containing four, O,N-coordinated o-iminobenzosemiquinonate(1−)π radical anions , 2003 .

[9]  V. Pecoraro,et al.  Catalytic oxidation of 3,5-Di-tert-butylcatechol by a series of mononuclear manganese complexes: synthesis, structure, and kinetic investigation. , 2003, Inorganic chemistry.

[10]  K. Wieghardt,et al.  A unique series of dinuclear transition metal-polyradical complexes with a m-phenylenediamine spacer and their catalytic reactivity. , 2003, Chemical communications.

[11]  J. W. Whittaker,et al.  Free radical catalysis by galactose oxidase. , 2003, Chemical reviews.

[12]  W. Kaim.  The chemistry and biochemistry of the copper–radical interaction , 2003 .

[13]  C. Sangregorio,et al.  HF-EPR to monitor electron transfer in mixed valence dioxolene metal complexes , 2003 .

[14]  Ho‐Hsiang Wei,et al.  Structure, magnetic properties and catecholase activity study of oxo-bridged dinuclear copper(II) complexes , 2002 .

[15]  E. Bill,et al.  Complexes of an aminebis(phenolate) [O,N,O] donor ligand and EPR studies of isoelectronic, isostructural Cr(III) and Mn(IV) complexes , 2002 .

[16]  M. Kinoshita,et al.  Molecular Magnetism—New Magnetic Materials , 2002 .

[17]  L. Rossi,et al.  Catecholase activity of a series of dicopper(II) complexes with variable Cu-OH(phenol) moieties. , 2002, Inorganic chemistry.

[18]  B. Krebs,et al.  The crystal structure of catechol oxidase: new insight into the function of type-3 copper proteins. , 2002, Accounts of chemical research.

[19]  K. Wieghardt,et al.  o-Iminobenzosemiquinonato complexes of Mn(III) and Mn(IV). Synthesis and characterization of [Mn(III)(L(ISQ))(2)(L(AP))] (S(t) = 1) and [Mn(IV)(L(ISQ))(2)(L(AP)-H)] (S(t) = 1/2). , 2002, Inorganic chemistry.

[20]  H. Pritzkow,et al.  Tuning the activity of catechol oxidase model complexes by geometric changes of the dicopper core. , 2002, Chemistry.

[21]  U. Flörke,et al.  Synthesis, Structure, Electrochemistry, and Magnetism of [MnIIIMnIII], [MnIIIFeIII] and [FeIIIFeIII] Cores: Generation of Phenoxyl Radical Containing [FeIIIFeIII] Species , 2001 .

[22]  D. Klemm,et al.  Copper(II) complexes of aminocarbohydrate beta-ketoenaminic ligands: efficient catalysts in catechol oxidation. , 2001, Chemistry.

[23]  K. Wieghardt,et al.  Electronic structure of bis(o-iminobenzosemiquinonato)metal complexes (Cu, Ni, Pd). The art of establishing physical oxidation states in transition-metal complexes containing radical ligands. , 2001, Journal of the American Chemical Society.

[24]  M. Palaniandavar,et al.  Models for the active site in galactose oxidase: Structure, spectra and redox of copper(II) complexes of certain phenolate ligands , 2000 .

[25]  O. Yamauchi,et al.  A Structural Model for the Galactose Oxidase Active Site which Shows Counteranion‐Dependent Phenoxyl Radical Formation by Disproportionation , 2000 .

[26]  T. D. Stack,et al.  Biomimetic modeling of copper oxidase reactivity. , 2000, Current opinion in chemical biology.

[27]  K. Wieghardt,et al.  Intramolecular Spin Interactions in Bis(phenoxyl)metal Complexes of Zinc(II) and Copper(II) , 1999 .

[28]  E. Monzani,et al.  Mechanistic, Structural, and Spectroscopic Studies on the Catecholase Activity of a Dinuclear Copper Complex by Dioxygen , 1999 .

[29]  K. Wieghardt,et al.  [Tris(o-iminosemiquinone)cobalt(III)]—a radical complex with an St = 3/2 ground state , 1999 .

[30]  J. Davies,et al.  Syntheses, structures and electrochemistry of copper(II) salicylaldehyde/tris(3-phenylpyrazolyl)borate complexes as models for the radical copper oxidases , 1999 .

[31]  James C. Sacchettini,et al.  Crystal structure of a plant catechol oxidase containing a dicopper center , 1998, Nature Structural Biology.

[32]  J. Stubbe,et al.  Protein Radicals in Enzyme Catalysis. , 1998, Chemical reviews.

[33]  Y. Deligiannakis,et al.  Metal ion–drug interactions. Preparation and properties of manganese (II), cobalt (II) and nickel (II) complexes of diclofenac with potentially interesting anti-inflammatory activity: Behavior in the oxidation of 3,5-di-tert-butyl-o-catechol , 1998 .

[34]  E. Monzani,et al.  Tyrosinase Models. Synthesis, Structure, Catechol Oxidase Activity, and Phenol Monooxygenase Activity of a Dinuclear Copper Complex Derived from a Triamino Pentabenzimidazole Ligand. , 1998, Inorganic chemistry.

[35]  R. S. Kelly,et al.  Probing the catalytic properties of copper(II) complexes of appended cyclams: correlations between catalysis and stability constants or electrochemical properties , 1998 .

[36]  J. Walker,et al.  Diphenol oxidases, enzyme-catalysed browning and plant disease resistance. , 1998, Biotechnology & genetic engineering reviews.

[37]  E. C. Wilkinson,et al.  Synthetic models of the inactive Copper(II)-tyrosinate and active Copper(II)-tyrosyl radical forms of galactose and glyoxal oxidases , 1997 .

[38]  C. Tommos,et al.  Tyrosyl radicals in enzyme catalysis: some properties and a focus on photosynthetic water oxidation. , 1997, Acta chemica Scandinavica.

[39]  S. Fukuzumi,et al.  Active Site Models for Galactose Oxidase. Electronic Effect of the Thioether Group in the Novel Organic Cofactor. , 1997, Inorganic chemistry.

[40]  I. Gautier-Luneau,et al.  A first model for the oxidized active form of the active site in galactose oxidase: a free-radical copper complex , 1997, JBIC Journal of Biological Inorganic Chemistry.

[41]  E. Spodine,et al.  Oxidation of 3,5-ditert-butylcatechol catalyzed by copper(II) complexes. A kinetic study , 1997 .

[42]  B. Krebs,et al.  Synthesis, structure and catecholase activity study of dinuclear copper(II) complexes† , 1997 .

[43]  E. Solomon,et al.  Multicopper Oxidases and Oxygenases. , 1996, Chemical reviews.

[44]  W. Haase,et al.  Structural and Functional Models for the Dinuclear Copper Active Site in Catechol Oxidases: Syntheses, X-ray Crystal Structures, Magnetic and Spectral Properties, and X-ray Absorption Spectroscopic Studies in Solid State and in Solution. , 1996, Inorganic chemistry.

[45]  A. Martell,et al.  Stoichiometric and catalytic oxidations by dinuclear copper(I) and copper(II) complexes of a Schiff base ligand derived from the 2:2 condensation of pyridine 2,6-dicarboxaldehyde and 1,5,9-triazanonane , 1996 .

[46]  L. Paquette,et al.  Asymmetric Synthesis of the Diterpenoid Marine Toxin (+)-Acetoxycrenulide , 1996 .

[47]  K. Inoue,et al.  High-spin polynitroxide radicals as versatile bridging ligands for transition metal complexes with high ferri/ferromagnetic Tc , 1996 .

[48]  O. Shadyro,et al.  SYNTHESIS AND ANTIOXIDANT PROPERTIES OF SOME DERIVATIVES OF ALKYLATED PYROCATECHOL , 1996 .

[49]  R. S. Kelly,et al.  Comparative study of the catalytic oxidation of catechols by copper(II) complexes of tripodal ligands , 1995 .

[50]  A. Rajca,et al.  Organic Diradicals and Polyradicals: From Spin Coupling to Magnetism? , 1994 .

[51]  K. Karlin,et al.  Structure and reactions of an eight-coordinate Mn(II) complex: [Mn(TMPA)2](ClO4)2 (TMPA=tris[(2-pyridyl)methyl]amine) , 1993 .

[52]  N. Arulsamy,et al.  Catalytic and magnetic properties of a new series of binuclear copper(II) complexes , 1991 .

[53]  Mitchell R. Malachowski,et al.  Novel mono- and binuclear Cu(II) complexes: synthesis, characterization and catecholase activity , 1989 .

[54]  P. A. Vigato,et al.  The preparation of binuclear complexes and their catalytic behaviour in the oxidation of 3,5-di-butycatechol , 1983 .

[55]  Kazuhiko Ida,et al.  Reaction between Various Copper(II) Complexes and Ascorbic Acid or 3,5-Di-t-butylcatechol , 1980 .