Frank Neese

Max Planck Institute for Chemical Energy Conversion, Mülheim-on-Ruhr, North Rhine-Westphalia, Germany

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Publications (395)2163.87 Total impact

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    ABSTRACT: The global energy and environmental concerns related to the excess CO2 concentration in the atmosphere have intensified the research and development regarding CO2 utilization. Due to the high stability and inertness of CO2, CO2 functionalization under mild conditions has been proven to be extremely challenging. Nature has, however, evolved efficient pathways to achieve this difficult transformation. Herein, we compare the mechanisms of CO2 two-electron reduction followed by synthetic catalysts and those by carbon monoxide dehydrogenase and formate dehydrogenase in order to provide more mechanistic insights into future catalyst design. Copyright © 2014 Elsevier Ltd. All rights reserved.
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    ABSTRACT: The domain based local pair natural orbital coupled cluster method with single-, double- and perturbative triple excitations (DLPNO-CCSD(T)) is an efficient quantum chemical method that allows for coupled cluster calculations on molecules with hundreds of atoms. Since coupled-cluster theory is the method of choice if high-accuracy is needed, DLPNO-CCSD(T) is very promising for large-scale chemical application. However, the various approximations that have to be introduced in order to reach near linear scaling also introduce limited deviations from the canonical results. In the present work, we investigate how far the accuracy of the DLPNO-CCSD(T) method can be pushed for chemical applications. We also address the question at which additional computational cost improvements, relative to the previously established default scheme, come. In order to answer these questions, a series of benchmark sets covering a broad range of quantum chemical applications including reaction energies, hydrogen bonds and other noncovalent interactions, conformer energies, and a prototype organometallic problem were selected. An accuracy of 1 kcal/mol or better can readily be obtained for all datasets using the default truncation scheme, which corresponds to the stated goal of the original implementation. Tightening of the three thresholds that control DLPNO leads to mean absolute errors and standard deviations from the canonical results of less than 0.25 kcal/mol (<1 kJ/mol). The price one has then to pay is an increased computational time by a factor close to 3. The applicability of the method is shown to be independent of the nature of the reaction. Based on the careful analysis of the results, three different sets of truncation thresholds (termed “LoosePNO”, “NormalPNO” and “TightPNO”) have been chosen for “black box” use of DLPNO-CCSD(T). This will allow users of the method to optimally balance performance and accuracy.
    Journal of Chemical Theory and Computation 03/2015; Just Accepted. DOI:10.1021/ct501129s · 5.39 Impact Factor
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    ABSTRACT: High-valent iron(IV)-oxo species are key intermediates in the catalytic cycles of a range of O2-activating iron enzymes. This work presents a detailed study of the electronic structures of mononuclear ([FeIV(O)(L)(NCMe)]2+, 1, L = tris(3,5-dimethyl-4-methoxylpyridyl-2-methyl)amine) and dinuclear ([(L)FeIV(O)(µ-O)FeIV(OH)(L)]3+, 2) iron(IV) complexes using absorption (ABS), magnetic circular dichroism (MCD) spectroscopy and wave-function-based quantum chemical calculations. For complex 1, the experimental MCD spectra at 2–10 K are dominated by a broad positive C-term band between 12000 and 18000 cm–1. As the temperature increases up to ~20 K, this feature is gradually replaced by a derivative-shaped pseudo-A term signal. The computed MCD spectra are in excellent agreement with experiment, which reproduce not only the excitation energies and the MCD signs of key transitions but also their temperature-dependent intensity variations. To further corroborate the assignments suggested by the calculations, the individual MCD sign for each transition is independently determined from the corresponding electron donating and accepting orbitals. Thus, unambiguous assignments can be made for the observed transitions in 1. The ABS/MCD data of complex 2 exhibit ten features that are assigned as ligand-field transitions or oxo- or hydroxo-to-metal charge transfer bands, based on MCD/ABS intensity ratios, calculated excitation energies, polarizations, and MCD signs. In comparison with complex 1, the electronic structure of the FeIV=O site is not significantly perturbed by the binding to another iron(IV) center. This may explain the experimental finding that complexes 1 and 2 have similar reactivities toward C-H bond activation and O-atom transfer.
    Chemical Science 02/2015; DOI:10.1039/C4SC03268C · 8.60 Impact Factor
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    ABSTRACT: Developing biomimetic complexes that model the active site of hydrogenase metalloenzymes in order to catalyze the activation of H2 is a topic of major interest. Here we report an EPR and computational investigation of a new heteroleptic nickel complex model, with relevance for H2 production, bearing a P2N2 ligand with proton relay in the second coordination sphere and a redox-active ligand in the first coordination sphere.
    Organometallics 02/2015; DOI:10.1021/acs.organomet.5b00039 · 4.25 Impact Factor
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    ABSTRACT: The azido ligand is one of the most investigated ligands in magnetochemistry. Despite its importance, not much is known about the ligand field of the azido ligand and its influence on magnetic anisotropy. We present here the electronic structure of a novel five coordinate Co(II)-azido (1) complex which has been characterized experimentally (magnetically and by electronic d-d absorption spectroscopy), and theoretically (by means of multi reference electronic structure methods). Static and dynamic magnetic data on 1 has been collected, the latter demonstrating a slow relaxation of the magnetization in an applied external magnetic field of H = 3000 Oe. Zero-field splitting parameters deduced from static susceptibility and magnetizations (D = -10.7 cm-1, E/D = 0.22) are in excellent agreement with the value of D inferred by Arrhenius plot of the magnetic relaxation time vs the temperature. Applying the so-called N-electron-valence-second order perturbation theory (NEVPT2) an excellent agreement between low-lying experimental and computed energies of d-d transition is demonstrated. Calculations were performed on 1 and a related four coordinate Co(II)-azido complex (2) lacking a fifth axial ligand. Based on these results and contrary to previous suggestions, the N3- ligand is shown to behave as a strong - and -donor. Magneto-structural correlations show a strong increase of the negative D with increasing Lewis basicity (shortening of the Co-N bond distances) of the axial ligand on the N3- site. The effect on the change of sign of D when going from four (positive D) to a five coordinated Co(II) (negative D) is discussed in the light of the bonding scheme derived from ligand field analysis of ab initio results.
    Journal of the American Chemical Society 01/2015; 137(5). DOI:10.1021/ja512232f · 11.44 Impact Factor
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    ABSTRACT: A central question in biological water splitting concerns the oxidation states of the manganese ions that comprise the oxygen-evolving complex of photosystem II. Understanding the nature and order of oxidation events that occur during the catalytic cycle of five Si states (i = 0–4) is of fundamental importance both for the natural system and for artificial water oxidation catalysts. Despite the widespread adoption of the so-called “high-valent scheme”—where, for example, the Mn oxidation states in the S2 state are assigned as III, IV, IV, IV—the competing “low-valent scheme” that differs by a total of two metal unpaired electrons (i.e. III, III, III, IV in the S2 state) is favored by several recent studies for the biological catalyst. The question of the correct oxidation state assignment is addressed here by a detailed computational comparison of the two schemes using a common structural platform and theoretical approach. Models based on crystallographic constraints were constructed for all conceivable oxidation state assignments in the four (semi)stable S states of the oxygen evolving complex, sampling various protonation levels and patterns to ensure comprehensive coverage. The models are evaluated with respect to their geometric, energetic, electronic, and spectroscopic properties against available experimental EXAFS, XFEL-XRD, EPR, ENDOR and Mn K pre-edge XANES data. New 2.5 K 55Mn ENDOR data of the S2 state are also reported. Our results conclusively show that the entire S state phenomenology can only be accommodated within the high-valent scheme by adopting a single motif and protonation pattern that progresses smoothly from S0 (III, III, III, IV) to S3 (IV, IV, IV, IV), satisfying all experimental constraints and reproducing all observables. By contrast, it was impossible to construct a consistent cycle based on the low-valent scheme for all S states. Instead, the low-valent models developed here may provide new insight into the over-reduced S states and the states involved in the assembly of the catalytically active water oxidizing cluster.
    Chemical Science 01/2015; 6(3). DOI:10.1039/C4SC03720K · 8.60 Impact Factor
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    ABSTRACT: Biological nitrogen fixation is enabled by molybdenum-dependent nitrogenase enzymes, which effect the reduction of dinitrogen to ammonia using an Fe7MoS9C active site, referred to as the iron molybdenum cofactor or FeMoco. In this mini-review, we summarize the current understanding of the molecular and electronic structure of FeMoco. The advances in our understanding of the active site structure are placed in context with the parallel evolution of synthetic model studies. The recent discovery of Mo(III) in the FeMoco active site is highlighted with an emphasis placed on the important role that model studies have played in this finding. In addition, the reactivities of synthetic models are discussed in terms of their relevance to the enzymatic system.
    JBIC Journal of Biological Inorganic Chemistry 12/2014; 20(2). DOI:10.1007/s00775-014-1230-6 · 3.16 Impact Factor
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    ABSTRACT: Developing biomimetic complexes that model the active site of [NiFe] hydrogenase enzymes in order to catalyze the activation of H2 is a topic of major interest. A functional [NiFe] hydrogenase model complex has recently been described by Ogo et al. (Science, 2013, 339, 682–683). Here, we report a Mössbauer and computational investigation of this model complex. This study affords deeper understanding of the electronic structure, the reactivity and the mechanism of H2 activation by this complex.
    Chemical Communications 12/2014; 51(11). DOI:10.1039/C4CC09035G · 6.38 Impact Factor
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    ABSTRACT: Ribonucleotide reductases (RNRs) catalyze the conversion of ribonucleotides to deoxyribonucleotides in all organisms. In all Class Ia RNRs, initiation of NDP reduction requires a reversible oxidation over 35 Å by a tyrosyl radical (Y122•, E. coli) in subunit β of a cysteine (C439) in the active site of subunit α. This radical transfer (RT) occurs by a specific pathway involving redox active tyrosines (Y122 ↔ Y356 in β to Y731 ↔ Y730 ↔ C439 in α); each oxidation necessitates loss of a proton coupled to loss of an electron (PCET). To study these steps, 3-aminotyrosine was site-specifically incorporated in place of Y356-β, Y731- and Y730- α, and each protein was incubated with the appropriate second subunit β(α), CDP and effector ATP to trap an amino tyrosyl radical (NH2Y•) in the active α2β2 complex. High-frequency (263 GHz) pulse EPR of the NH2Y•s reported the gx values with unprecedented resolution and revealed strong electrostatic effects caused by the protein environment. (2)H ENDOR spectroscopy accompanied by quantum chemical calculations provided spectroscopic evidence for hydrogen bond interactions at the radical sites, i.e. two exchangeable H bonds to NH2Y730•, one to NH2Y731• and none to NH2Y356•. Similar experiments with double mutants α-NH2Y730/C439A and α-NH2Y731/Y730F allowed assignment of the H bonding partner(s) to a pathway residue(s) providing direct evidence for co-linear PCET within α. The implications of these observations for the PCET process within α and at the interface are discussed.
    Journal of the American Chemical Society 12/2014; 137(1). DOI:10.1021/ja510513z · 11.44 Impact Factor
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    ABSTRACT: One of the biggest challenges in studying catalytic reactions is characterizing intermediate states and identifying reaction pathways. Oftentimes, intermediate states with unpaired electrons are formed which provide an opportunity to study the compound via electron paramagnetic resonance (EPR). Combining EPR with density functional theory (DFT) represents a powerful synergistic approach to accomplish these goals. Once the catalytic intermediates and reaction pathway are known, rate-limiting steps critical to parameters like overpotential and turnover number may be identified and eliminated. In this study 1,3,5-triphenyl verdazyl is examined using continuous-wave-EPR, electron nuclear double resonance and DFT as an instructive example of how theory and experiment can complement each other to find the reactive electron. The methods and concomitant analysis have been presented in didactic fashion and with emphasis on the strengths and weaknesses of the methods.
    Applied Magnetic Resonance 12/2014; DOI:10.1007/s00723-014-0627-2 · 1.15 Impact Factor
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    ABSTRACT: A molybdenum L-edge X-ray absorption spectroscopy (XAS) study is presented for native and oxidized MoFe protein of nitrogenase as well as Mo-Fe model compounds. Recently collected data on MoFe protein (in oxidized and reduced forms) is compared to previously published Mo XAS data on the isolated FeMo cofactor in NMF solution and put in context of the recent Mo K-edge XAS study, which showed a MoIII assignment for the molybdenum atom in FeMoco. The L3-edge data are interpreted within a simple ligand-field model, from which a time-dependent density functional theory (TDDFT) approach is proposed as a way to provide further insights into the analysis of the molybdenum L3-edges. The calculated results reproduce well the relative spectral trends that are observed experimentally. Ultimately, these results give further support for the MoIII assignment in protein-bound FeMoco, as well as isolated FeMoco.
    Zeitschrift für anorganische Chemie 11/2014; 641(1). DOI:10.1002/zaac.201400446 · 1.25 Impact Factor
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    ABSTRACT: The interpretation of electron paramagnetic resonance spectra of polynuclear transition metal complexes in terms of individual contributions from each paramagnetic center can be greatly facilitated by the availability of theoretical methods that enable the reliable prediction of local spectroscopic parameters. In this work we report an approach that enables the application of multireference ab initio methods for the calculation of local zero field splitting tensors, one of the leading terms in the spin Hamiltonian for exchange-coupled systems of high nuclearity. The method referred to as local complete active space configuration interaction (L-CASCI) represents a multireference calculation with an active space composed of local orbitals of the center of interest. By successive permutation of the active space to include the localized orbitals corresponding to a particular center of the complex, all on-site parameters can be easily obtained at a high-level of theory with a corresponding low computational cost. Benchmark calculations on synthetic complexes confirm the validity of the approach. As an example of the applicability of the L-CASCI method to large systems, we determine the local anisotropy of the Mn(III) ion of the tetranuclear manganese cluster of photosystem II in both structural forms of its S2 state.
    Inorganic Chemistry 10/2014; 53(21). DOI:10.1021/ic502081c · 4.79 Impact Factor
  • Christian Kollmar, Frank Neese
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    ABSTRACT: The role of the static Kohn-Sham (KS) response function describing the response of the electron density to a change of the local KS potential is discussed in both the theory of the optimized effective potential (OEP) and the so-called inverse Kohn-Sham problem involving the task to find the local KS potential for a given electron density. In a general discussion of the integral equation to be solved in both cases, it is argued that a unique solution of this equation can be found even in case of finite atomic orbital basis sets. It is shown how a matrix representation of the response function can be obtained if the exchange-correlation potential is expanded in terms of a Schmidt-orthogonalized basis comprising orbitals products of occupied and virtual orbitals. The viability of this approach in both OEP theory and the inverse KS problem is illustrated by numerical examples.
    The Journal of Chemical Physics 10/2014; 141(13):134106. DOI:10.1063/1.4896897 · 3.12 Impact Factor
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    ABSTRACT: The recently described intermolecular O2 transfer between the side-on Ni-O2 complex [(12-TMC)Ni-O2]+ and the manganese complex [(14-TMC)Mn]2+, where 12-TMC and 14-TMC are 12- and 14-membered macrocyclic ligands, 12-TMC=1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane and 14-TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, is studied by means of DFT methods. B3LYP calculations including long-range corrections and solvent effects are performed to elucidate the mechanism. The potential energy surfaces (PESs) compatible with different electronic states of the reactants have been analyzed. The calculations confirm a two-step reaction, with a first rate-determining bimolecular step and predict the exothermic character of the global process. The relative stability of the products and the reverse barrier are in line with the fact that no reverse reaction is experimentally observed. An intermediate with a m-h1:h1-O2 coordination and two transition states are identified on the triplet PES, slightly below the corresponding stationary points of the quintet PES, suggesting an intersystem crossing before the first transition state. The calculated activation parameters and the relative energies of the two transition sates and the products are in very good agreement with the experimental data. The calculations suggest that a superoxide anion is transferred during the reaction.
    Chemistry - A European Journal 10/2014; 20. DOI:10.1002/chem.201403233 · 5.93 Impact Factor
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    ABSTRACT: The reaction FeO+ + H2 → Fe+ + H2O is a simple model for hydrogen abstraction processes in biologically important heme systems. The geometries of all relevant stationary points on the lowest sextet and quartet surfaces were optimized using several density functionals as well as the CASSCF method. The corresponding energy profiles were computed at the following levels: density functional theory using gradient-corrected, hybrid, meta, hybrid-meta, and perturbatively corrected double hybrid functionals; single-reference coupled cluster theory including up to single, double, triple, and perturbative quadruple excitations [CCSDT(Q)]; correlated multireference ab initio methods (MRCI, MRAQCC, SORCI, SORCP, MRMP2, NEVPT2, and CASPT2). The calculated energies were corrected for scalar relativistic effects, zero-point vibrational energies, and core−valence correlation effects. MRCI and SORCI energies were corrected for size-consistency errors using an a posteriori Davidson correction (+Q) leading to MRCI+Q and SORCI+Q. Comparison with the available experimental data shows that CCSDT(Q) is most accurate and can thus serve as benchmark method for this electronically challenging reaction. Among the density functionals, B3LYP performs best. In the correlated ab initio calculations with a full-valence active space, SORCI+Q yields the lowest deviations from the CCSDT(Q) reference results, with qualitatively similar energy profiles being obtained from MRCI+Q and MRAQCC. SORCI+Q benefits from the quality of the approximate average natural orbitals used in the final step of the SORCI procedure. Many of the tested methods show surprisingly large errors. The present results validate the common use of B3LYP in computational studies of heme systems and offer guidance on which correlated ab initio methods are most suitable for such studies.
    Journal of Chemical Theory and Computation 09/2014; 10(9):3807−3820. DOI:10.1021/ct500522d · 5.39 Impact Factor
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    ABSTRACT: The electronic structure of the Mn/Fe cofactor identified in a new class of oxidases (R2lox) described by Andersson and Högbom [Proc. Natl. Acad. Sci. U. S. A. 2009, 106, 5633] is reported. The R2lox protein is homologous to the small subunit of class Ic ribonucleotide reductase (R2c), but has a completely different in vivo function. Using multifrequency EPR and related pulse techniques, it is shown that the cofactor of R2lox represents an antiferromagnetically coupled Mn(III)/Fe(III) dimer linked by a μ-hydroxo/bis-μ-carboxylato bridging network. The Mn(III) ion is coordinated by a single water ligand. The R2lox cofactor is photoactive, converting into a second form (R2loxPhoto) upon visible illumination at cryogenic temperatures (77 K) that completely decays upon warming. This second, unstable form of the cofactor more closely resembles the Mn(III)/Fe(III) cofactor seen in R2c. It is shown that the two forms of the R2lox cofactor differ primarily in terms of the local site geometry and electronic state of the Mn(III) ion, as best evidenced by a reorientation of its unique (55)Mn hyperfine axis. Analysis of the metal hyperfine tensors in combination with density functional theory (DFT) calculations suggest that this change is triggered by deprotonation of the μ-hydroxo bridge. These results have important consequences for mixed-metal R2c cofactor and the divergent chemistry these two systems perform.
    Journal of the American Chemical Society 08/2014; 136(38). DOI:10.1021/ja507435t · 11.44 Impact Factor
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    ABSTRACT: At variance with ferredoxins, Rieske-type proteins contain a chemically asymmetric iron–sulfur cluster. Nevertheless, X-ray crystallography apparently finds their [2Fe–2S] cores to be structurally symmetric or very close to symmetric (i.e. the four iron–sulfur bonds in the [2Fe– 2S] core are equidistant). Using a combination of advanced density-based approaches, including finite-temperature molecular dynamics to access thermal fluctuations and free-energy profiles, in conjunction with correlated wave- function-based methods we clearly predict an asymmetric core structure. This reveals a fundamental and intrinsic difference within the iron–sulfur clusters hosted by Rieske proteins and ferredoxins and thus opens up a new dimension for the ongoing efforts in understanding the role of Rieske-type [2Fe–2S] cluster in electron transfer processes that occur in almost all biological systems.
    JBIC Journal of Biological Inorganic Chemistry 08/2014; DOI:10.1007/s00775-014-1185-7 · 3.16 Impact Factor
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    ABSTRACT: FeS clusters are a universal biological motif. They carry out electron transfer, redox chemistry, and even oxygen sensing, in diverse processes including nitrogen fixation, respiration, and photosynthesis. The low-lying electronic states are key to their remarkable reactivity, but cannot be directly observed. Here we present the first ever quantum calculation of the electronic levels of [2Fe-2S] and [4Fe-4S] clusters free from any model assumptions. Our results highlight limitations of long-standing models of their electronic structure. In particular, we demonstrate that the widely used Heisenberg-Double-Exchange model underestimates the number of states by 1-2 orders of magnitude, which can conclusively be traced to the absence of Fe d$\rightarrow$d excitations, thought to be important in these clusters. Further, the electronic energy levels of even the same spin are dense on the scale of vibrational fluctuations, and this provides a natural explanation for the ubiquity of these clusters in nature for catalyzing reactions.
    Nature Chemistry 08/2014; 6(10). DOI:10.1038/nchem.2041 · 23.30 Impact Factor
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    ABSTRACT: Two monochromium(III)-containing heteropolytungstates, [Cr(III)(HP(V)W7O28)2](13-) (1a) and [Cr(III)(HAs(V)W7O28)2](13-) (2a), were prepared via simple, one-pot reactions in aqueous, basic medium, by reaction of the composing elements, and then isolated as hydrated sodium salts, Na13[Cr(III)(HP(V)W7O28)2]·47H2O (1) and Na13[Cr(III)(HAs(V)W7O28)2]·52H2O (2). Polyanions 1a and 2a comprise an octahedrally coordinated Cr(III) ion, sandwiched by two {PW7} or {AsW7} units. Both compounds 1 and 2 were fully characterized in the solid state by single-crystal XRD, IR spectroscopy, thermogravimetric and elemental analyses, magnetic susceptibility, and EPR measurements. Magnetic studies on 1 and 2 demonstrated that both compounds exhibit appreciable deviation from typical paramagnetic behavior, and have a ground state S = (3)/2, as expected for a Cr(III) ion, but with an exceptionally large zero-field uniaxial anisotropy parameter (D). EPR measurements on powder and single-crystal samples of 1 and 2 using 9.5, 34.5, and 239.2 GHz frequencies and over 4-295 K temperature fully support the magnetization results and show that D = +2.4 cm(-1), the largest and sign-assigned D-value so far reported for an octahedral Cr(III)-containing, molecular compound. Ligand field analysis of results from CASSCF and NEVPT2-correlated electronic structure calculations on Cr(OH)6(3-) model complexes allowed to unravel the crucial role of the second coordination sphere of Cr(III) for the unusually large magnetic anisotropy reflected by the experimental value of D. The newly developed theoretical modeling, combined with the synthetic procedure for producing such unusual magnetic molecules in a well-defined and essentially magnetically isolated environment, appears to be a versatile new research area.
    ChemInform 08/2014; 53(17). DOI:10.1021/ic501385r
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    ABSTRACT: The photosynthetic protein complex photosystem II oxidizes water to molecular oxygen at an embedded tetramanganese-calcium cluster. Resolving the geometric and electronic structure of this cluster in its highest metastable catalytic state (designated S3) is a prerequisite for understanding the mechanism of O-O bond formation. Here, multifrequency, multidimensional magnetic resonance spectroscopy reveals that all four manganese ions of the catalyst are structurally and electronically similar immediately before the final oxygen evolution step; they all exhibit a 4+ formal oxidation state and octahedral local geometry. Only one structural model derived from quantum chemical modeling is consistent with all magnetic resonance data; its formation requires the binding of an additional water molecule. O-O bond formation would then proceed by the coupling of two proximal manganese-bound oxygens in the transition state of the cofactor.
    Science 08/2014; 345(6198):804-8. DOI:10.1126/science.1254910 · 31.48 Impact Factor

Publication Stats

14k Citations
2,163.87 Total Impact Points


  • 2012–2015
    • Max Planck Institute for Chemical Energy Conversion
      Mülheim-on-Ruhr, North Rhine-Westphalia, Germany
    • Bulgarian Academy of Sciences
      • Institute of General and Inorganic Chemistry
      Ulpia Serdica, Sofia-Capital, Bulgaria
  • 2014
    • Jacobs University
      • SES - School of Engineering & Science
      Bremen, Bremen, Germany
  • 2004–2013
    • Max Planck Institute for Chemistry
      Mayence, Rheinland-Pfalz, Germany
    • Utrecht University
      Utrecht, Utrecht, Netherlands
  • 2010–2012
    • University Joseph Fourier - Grenoble 1
      • • Département de chimie moléculaire
      • • Institut de Chimie Moléculaire de Grenoble
      Grenoble, Rhône-Alpes, France
    • San Diego Zoo
      San Diego, California, United States
  • 2009–2012
    • University of Rochester
      • Department of Chemistry
      Rochester, NY, United States
    • University of Maryland, Baltimore
      Baltimore, Maryland, United States
  • 2006–2012
    • University of Bonn
      • Institute of Physical and Theoretical Chemistry
      Bonn, North Rhine-Westphalia, Germany
  • 2011
    • National and Kapodistrian University of Athens
      • Division of Biochemistry
      Athens, Attiki, Greece
    • Institut Laue-Langevin
      Grenoble, Rhône-Alpes, France
    • University of Toulouse
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 2007–2011
    • University of Münster
      • Institute of Organic Chemistry
      Münster, North Rhine-Westphalia, Germany
    • University of Vermont
      • Department of Chemistry
      Burlington, Vermont, United States
    • University of Copenhagen
      • Department of Chemistry
      Copenhagen, Capital Region, Denmark
  • 2006–2011
    • Cornell University
      • Department of Chemistry and Chemical Biology
      Ithaca, NY, United States
  • 2002–2011
    • Weizmann Institute of Science
      • Department of Chemical Physics
    • Universitätsklinikum Erlangen
      Erlangen, Bavaria, Germany
    • California Institute of Technology
      Pasadena, California, United States
  • 1998–2010
    • Stanford University
      • Department of Chemistry
      Stanford, CA, United States
  • 2005–2009
    • The University of Arizona
      • Department of Chemistry and Biochemistry (College of Science)
      Tucson, AZ, United States
    • Max Planck Institute for Coal Research
      Mülheim-on-Ruhr, North Rhine-Westphalia, Germany
    • Universität Stuttgart
      Stuttgart, Baden-Württemberg, Germany
    • Universität Paderborn
      • Department of Physics
      Paderborn, North Rhine-Westphalia, Germany
    • Christian-Albrechts-Universität zu Kiel
      • Institute of Inorganic Chemistry
      Kiel, Schleswig-Holstein, Germany
  • 2008
    • Ruhr-Universität Bochum
      Bochum, North Rhine-Westphalia, Germany
    • Paul Sabatier University - Toulouse III
      • Laboratoire de Chimie et Physique Quantiques - UMR 5626 - LCPQ
      Toulouse, Midi-Pyrenees, France
  • 2007–2008
    • University of Wisconsin, Madison
      • • Department of Chemistry
      • • Department of Biochemistry
      Mississippi, United States
  • 1996–2002
    • Universität Konstanz
      • Faculty of Sciences
      Constance, Baden-Württemberg, Germany