Reactivity of copper(II)-alkylperoxo complexes.

Copper(II) complexes 1a and 1b, supported by tridentate ligand bpa [bis(2-pyridylmethyl)amine] and tetradentate ligand tpa [tris(2-pyridylmethyl)amine], respectively, react with cumene hydroperoxide (CmOOH) in the presence of triethylamine in CH(3)CN to provide the corresponding copper(II) cumylperoxo complexes 2a and 2b, the formation of which has been confirmed by resonance Raman and ESI-MS analyses using (18)O-labeled CmOOH. UV-vis and ESR spectra as well as DFT calculations indicate that 2a has a 5-coordinate square-pyramidal structure involving CmOO(-) at an equatorial position and one solvent molecule at an axial position at low temperature (-90 °C), whereas a 4-coordinate square-planar structure that has lost the axial solvent ligand is predominant at higher temperatures (above 0 °C). Complex 2b, on the other hand, has a typical trigonal bipyramidal structure with the tripodal tetradentate tpa ligand, where the cumylperoxo ligand occupies an axial position. Both cumylperoxo copper(II) complexes 2a and 2b are fairly stable at ambient temperature, but decompose at a higher temperature (60 °C) in CH(3)CN. Detailed product analyses and DFT studies indicate that the self-decomposition involves O-O bond homolytic cleavage of the peroxo moiety; concomitant hydrogen-atom abstraction from the solvent is partially involved. In the presence of 1,4-cyclohexadiene (CHD), the cumylperoxo complexes react smoothly at 30 °C to give benzene as one product. Detailed product analyses and DFT studies indicate that reaction with CHD involves concerted O-O bond homolytic cleavage and hydrogen-atom abstraction from the substrate, with the oxygen atom directly bonded to the copper(II) ion (proximal oxygen) involved in the C-H bond activation step.

[1]  K. Karlin,et al.  Spectroscopic and computational characterization of CuII-OOR (R = H or cumyl) complexes bearing a Me6-tren ligand. , 2011, Dalton transactions.

[2]  G. DiLabio,et al.  Diffusion controlled hydrogen atom abstraction from tertiary amines by the benzyloxyl radical. The importance of C-H/N hydrogen bonding. , 2011, Organic letters.

[3]  Michael T. Green,et al.  X-ray absorption spectroscopy and reactivity of thiolate-ligated Fe(III)-OOR complexes. , 2010, Inorganic chemistry.

[4]  Amy A Sarjeant,et al.  Influence of the nitrogen donors on nonheme iron models of superoxide reductase: high-spin Fe(III)-OOR complexes. , 2010, Journal of the American Chemical Society.

[5]  Donald G Truhlar,et al.  Density functional theory for transition metals and transition metal chemistry. , 2009, Physical chemistry chemical physics : PCCP.

[6]  L. Que,et al.  Reactivities of Fe(IV) complexes with oxo, hydroxo, and alkylperoxo ligands: an experimental and computational study. , 2009, Inorganic chemistry.

[7]  C. Cramer,et al.  Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions. , 2009, The journal of physical chemistry. B.

[8]  F. Neese.  Prediction of molecular properties and molecular spectroscopy with density functional theory: From fundamental theory to exchange-coupling , 2009 .

[9]  K. Karlin,et al.  Copper-dioxygen complex mediated C-H bond oxygenation: relevance for particulate methane monooxygenase (pMMO). , 2009, Current opinion in chemical biology.

[10]  Michael T. Green,et al.  Rational tuning of the thiolate donor in model complexes of superoxide reductase: direct evidence for a trans influence in Fe(III)-OOR complexes. , 2008, Journal of the American Chemical Society.

[11]  C. Cramer,et al.  Reactions of copper(II)-H2O2 adducts supported by tridentate bis(2-pyridylmethyl)amine ligands: sensitivity to solvent and variations in ligand substitution. , 2008, Inorganic chemistry.

[12]  S. Nakashima,et al.  Reactivity of mononuclear alkylperoxo copper(II) complex. O-O bond cleavage and C-H bond activation. , 2008, Journal of the American Chemical Society.

[13]  L. Rout,et al.  Recent advances in copper-catalyzed oxidation of organic compounds , 2008 .

[14]  M. Costas,et al.  X-ray absorption spectroscopic studies of high-spin nonheme (alkylperoxo)iron(III) intermediates. , 2007, Inorganic chemistry.

[15]  G. van Koten,et al.  Characterization and alkane oxidation activity of a diastereopure seven-coordinate iron(III) alkylperoxo complex. , 2007, Dalton transactions.

[16]  E. Kovaleva,et al.  Crystal Structures of Fe2+ Dioxygenase Superoxo, Alkylperoxo, and Bound Product Intermediates , 2007, Science.

[17]  L. Que,et al.  Kinetic analysis of the conversion of nonheme (alkylperoxo)iron(III) species to iron(IV) complexes. , 2007, Inorganic chemistry.

[18]  K. Yoshizawa,et al.  Experimental and theoretical evidence for nonheme iron(III) alkylperoxo species as sluggish oxidants in oxygenation reactions. , 2007, Angewandte Chemie.

[19]  D. Truhlar,et al.  A new local density functional for main-group thermochemistry, transition metal bonding, thermochemical kinetics, and noncovalent interactions. , 2006, The Journal of chemical physics.

[20]  Amy A. Narducci Sarjeant,et al.  A low-spin alkylperoxo-iron(III) complex with weak Fe-O and O-O bonds: implications for the mechanism of superoxide reductase. , 2006, Journal of the American Chemical Society.

[21]  P. Comba,et al.  Spin-crossover in an iron(III)-bispidine-alkylperoxide system. , 2006, Inorganic chemistry.

[22]  Roberto Improta,et al.  A state-specific polarizable continuum model time dependent density functional theory method for excited state calculations in solution. , 2006, The Journal of chemical physics.

[23]  S. Itoh.  Mononuclear copper active-oxygen complexes. , 2006, Current opinion in chemical biology.

[24]  L. Que,et al.  High-valent nonheme iron. Two distinct iron(IV) species derived from a common iron(II) precursor. , 2005, Journal of the American Chemical Society.

[25]  L. Que,et al.  Spin-state rationale for the peroxo-stabilizing role of the thiolate ligand in superoxide reductase. , 2005, Angewandte Chemie.

[26]  Mi Hee Lim,et al.  Structural insights into nonheme alkylperoxoiron(III) and oxoiron(IV) intermediates by X-ray absorption spectroscopy. , 2004, Journal of the American Chemical Society.

[27]  The reaction of [FeII(tpa)] with H2O2 in acetonitrile and acetone--distinct intermediates and yet similar catalysis. , 2004, Chemistry.

[28]  T. D. Stack,et al.  Structure and spectroscopy of copper-dioxygen complexes. , 2004, Chemical reviews.

[29]  L. Que,et al.  Dioxygen activation at mononuclear nonheme iron active sites: enzymes, models, and intermediates. , 2004, Chemical reviews.

[30]  William B Tolman,et al.  Reactivity of dioxygen-copper systems. , 2004, Chemical reviews.

[31]  J. Harvey,et al.  DFT computation of relative spin-state energetics of transition metal compounds , 2004 .

[32]  E. P. Talsi,et al.  Stability of low-spin ferric hydroperoxo and alkylperoxo complexes with tris(2-pyridylmethyl)amine , 2003 .

[33]  L. Que,et al.  A dramatic push effect on the homolysis of FeIII(OOR) intermediates to form non-heme FeIV=O complexes. , 2003, Angewandte Chemie.

[34]  Claire M. Jones,et al.  EPR spin-trapping evidence for the direct, one-electron reduction of tert-butylhydroperoxide to the tert-butoxyl radical by copper(II): paradigm for a previously overlooked reaction in the initiation of lipid peroxidation. , 2003, Journal of the American Chemical Society.

[35]  I. Ciofini,et al.  DFT calculations of molecular magnetic properties of coordination compounds , 2003 .

[36]  L. Que,et al.  Biomimetic aryl hydroxylation derived from alkyl hydroperoxide at a nonheme iron center. Evidence for an Fe(IV)=O oxidant. , 2003, Journal of the American Chemical Society.

[37]  N. Lehnert,et al.  Electronic structure and reactivity of high-spin iron--alkyl- and--pterinperoxo complexes. , 2003, Inorganic chemistry.

[38]  S. Hikichi,et al.  Inorganic chemistry based on Tp ligands: From dioxygen complexes to organometallic systems , 2002 .

[39]  M. Salamone,et al.  Spectral properties and absolute rate constants for beta-scission of ring-substituted cumyloxyl radicals. A laser flash photolysis study. , 2002, The Journal of organic chemistry.

[40]  L. Que,et al.  Electronic structure of high-spin iron(III)-alkylperoxo complexes and its relation to low-spin analogues: reaction coordinate of O-O bond homolysis. , 2001, Journal of the American Chemical Society.

[41]  M. Burkitt.  A critical overview of the chemistry of copper-dependent low density lipoprotein oxidation: roles of lipid hydroperoxides, alpha-tocopherol, thiols, and ceruloplasmin. , 2001, Archives of biochemistry and biophysics.

[42]  T. Uchimaru,et al.  Dinucleotide Hydrolysis Promoted by Dinuclear Zn Complexes − The Effect of the Distance between Zn Ions in the Complexes on the Hydrolysis Rate , 2001 .

[43]  L. Que,et al.  Spectroscopic properties and electronic structure of low-spin Fe(III)-alkylperoxo complexes: homolytic cleavage of the O-O bond. , 2001, Journal of the American Chemical Society.

[44]  L. Que,et al.  "Intermolecular" trapping of a nonheme Fe(IV)=O intermediate. , 2001, Inorganic chemistry.

[45]  E. C. Wilkinson,et al.  A nonheme iron(II) complex that models the redox cycle of lipoxygenase , 2001, JBIC Journal of Biological Inorganic Chemistry.

[46]  A. Sobolev,et al.  Stability and reactivity of low-spin ferric hydroperoxo and alkylperoxo complexes with bipyridine and phenantroline ligands , 2000 .

[47]  Peng Chen,et al.  Spectroscopic and Theoretical Studies of Mononuclear Copper(II) Alkyl- and Hydroperoxo Complexes: Electronic Structure Contributions to Reactivity , 2000 .

[48]  L. Que,et al.  Biomimetic nonheme iron catalysts for alkane hydroxylation , 2000 .

[49]  F. A. Chavez,et al.  Co(III)-alkylperoxo complexes: syntheses, structure-reactivity correlations, and use in the oxidation of hydrocarbons. , 2000, Accounts of chemical research.

[50]  Y. Kitagawa,et al.  Ab initio computations of effective exchange integrals for H–H, H–He–H and Mn2O2 complex: comparison of broken-symmetry approaches , 2000 .

[51]  S. Hikichi,et al.  New aspects of the cobalt-dioxygen complex chemistry opened by hydrotris(pyrazoly)borate ligands (TpR): unique properties of TpRCo-dioxygen complexes , 2000 .

[52]  T. Uchida,et al.  An approach to the O2 activating mononuclear non-heme Fe enzymes: structural characterization of Fe(II)–acetato complex and formation of alkylperoxoiron(III) species with the highly hindered hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate , 2000 .

[53]  H. Masuda,et al.  Synthesis and Characterization of Novel Alkylperoxo Mononuclear Iron(III) Complexes with a Tripodal Pyridylamine Ligand: A Model for Peroxo Intermediates in Reactions Catalyzed by Non-Heme Iron Enzymes. , 1999, Inorganic chemistry.

[54]  L. Que,et al.  Evidence for a Nonheme Fe(IV)O Species in the Intramolecular Hydroxylation of a Phenyl Moiety , 1999 .

[55]  Axel D. Becke,et al.  Optimized density functionals from the extended G2 test set , 1998 .

[56]  S. Fukuzumi,et al.  Model studies on calcium-containing quinoprotein alcohol dehydrogenases. Catalytic role of Ca2+ for the oxidation of alcohols by coenzyme PQQ (4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2, 7,9-tricarboxylic acid). , 1998, Biochemistry.

[57]  I. Arends,et al.  Oxygen activation by metal complexes and alkyl hydroperoxides. Applications of mechanistic probes to explore the role of alkoxyl radicals in alkane functionalization , 1997 .

[58]  K. Karlin,et al.  XAS Structural Comparisons of Reversibly Interconvertible Oxo- and Hydroxo-Bridged Heme-Copper Oxidase Model Compounds , 1996 .

[59]  E. C. Wilkinson,et al.  An Alkylperoxoiron(III) Intermediate and Its Role in the Oxidation of Aliphatic CH Bonds , 1995 .

[60]  D. Case,et al.  Orbital interactions, electron delocalization and spin coupling in iron-sulfur clusters , 1995 .

[61]  E. C. Wilkinson,et al.  Formation of an Alkylperoxoiron(III) Complex during Oxidations Catalyzed by μ‐Oxodiiron(III) Complexes , 1995 .

[62]  Y. Iwata,et al.  Synthesis, molecular structure, and reactivity of (alkylperoxo)copper(II) complex , 1993 .

[63]  K. Karlin,et al.  Reversible reaction of O2 (and CO) with a copper(I) complex. X-ray structures of relevant mononuclear Cu(I) precursor adducts and the trans-(μ-1,2-peroxo)dicopper(II) product , 1993 .

[64]  T. Egawa,et al.  Roles of proximal ligand in heme proteins: replacement of proximal histidine of human myoglobin with cysteine and tyrosine by site-directed mutagenesis as models for P-450, chloroperoxidase, and catalase. , 1993, Biochemistry.

[65]  C. E. Brown,et al.  Solvent effects on the competitive .beta.-scission and hydrogen atom abstraction reactions of the cumyloxyl radical. Resolution of a long-standing problem , 1993 .

[66]  L. Que,et al.  A High-Potential Ferrous Complex and Its Conversion to an Alkylperoxoiron(III) Intermediate. A Lipoxygenase Model , 1993 .

[67]  M. Finn,et al.  Mechanism of asymmetric epoxidation. 2. Catalyst structure , 1991 .

[68]  Frank Jensen,et al.  A spin correction procedure for unrestricted Hartree-Fock and Møller-Plesset wavefunctions for singlet diradicals and polyradicals , 1988 .

[69]  Michael Dolg,et al.  Energy‐adjusted ab initio pseudopotentials for the first row transition elements , 1987 .

[70]  Louis Noodleman,et al.  Valence bond description of antiferromagnetic coupling in transition metal dimers , 1981 .

[71]  Arvi Rauk,et al.  On the calculation of multiplet energies by the hartree-fock-slater method , 1977 .