Peter Mayer

Ludwig-Maximilians-University of Munich, München, Bavaria, Germany

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Publications (450)1253.12 Total impact


    Journal of Chemical Sciences 11/2015; DOI:10.1007/s12039-015-0925-8 · 1.19 Impact Factor
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    ABSTRACT: From X-ray structure analysis, amino twist angles of 90.0o for 2,4-dimethyl-3-(dimethylamino)benzonitrile (mMMD), 82.7o for 4-(di-tert-butylamino)benzonitrile (DTABN), and 88.7o for 6-cyanobenzoquinuclidine (CBQ) are determined, all considerably larger than the 57.4o of 3,5-dimethyl-4-(dimethylamino)benzonitrile (MMD). This large twist leads to lengthening of the amino-phenyl bond, 143.5 pm (mMMD), 144.1 pm (DTABN), 144.6 pm (CBQ), and 141.4 pm (MMD), as compared with 136.5 pm for the planar 4-(dimethylamino)benzonitrile (DMABN). As a consequence, the electronic coupling between the amino and phenyl subgroups in mMMD, DTABN, CBQ, and MMD is much weaker than in DMABN, as seen from the strongly reduced molar absorption coefficients. The fluorescence spectrum of MMD in n-hexane at 25 oC consists of two emissions from a locally excited (LE) and an intramolecular charge transfer (ICT) state, with a fluorescence quantum yield ratio ´(ICT)/(LE) of 12.8. In MeCN, a single ICT emission is found. With mMMD in n-hexane, in contrast, only LE fluorescence is observed, whereas the spectrum in MeCN originates from the ICT state. These differences are also seen from the halfwidths of the overall fluorescence bands, which in n-hexane are larger for MMD than for mMMD, decreasing with solvent polarity for MMD and increasing for mMMD, reflecting the disappearance of LE and the onset of ICT in the overall spectra, respectively. From solvatochromic measurements the dipole moments e(ICT) of MMD (16 D) and mMMD (15 D) are obtained. Femtosecond excited state absorption (ESA) spectra at 22 oC reveal that MMD in n-hexane undergoes a reversible LE⇄ICT reaction, with LE as the precursor, with a forward rate constant ka = 5.6 x 1012 s 1 and a back reaction kd  0.05 x 1012 s-1. With MMD in the strongly polar solvent MeCN, ICT is faster: ka = 10 x 1012 s-1. In the case of mMMD in n-hexane, the ESA spectra show that ICT does not take place, contrary to MeCN, in which ka = 2.5 x 1012 s-1. The ICT reactions with MMD and mMMD are much faster than that of the parent compound DMABN in MeCN, with ka = 0.24 x 1012 s-1. Because of the very short ICT reaction times of 180 fs (MMD, n-hexane), 100 fs (MMD, MeCN) and 400 fs (mMMD, MeCN), it is clear that the picosecond fluorescence decays of these systems appear to be single exponential, due to the insufficient time resolution of 3 ps. It is concluded that the faster LE  ICT reaction of MMD as compared with DMABN (ka = 0.24 x 1012 s-1 in MeCN) is caused by a smaller energy gap E(S1,S2) between the lowest singlet excited states and not by the large amino twist angle. Similarly, the larger E(S1,S2) of mMMD as compared with MMD is held responsible for its smaller ICT efficiency (no reaction in n-hexane).
    The Journal of Physical Chemistry A 11/2015; DOI:10.1021/acs.jpca.5b09368 · 2.69 Impact Factor
  • Varvara Morozova · Peter Mayer · Guillaume Berionni ·
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    ABSTRACT: Several phosphonium and ammonium triarylborohydrides, which are intermediates in hydrogenation reactions catalyzed by frustrated Lewis pairs, were synthesized in high yield under mild conditions from triaryl boranes, ammonium or phosphonium halides, and triethylsilane. The kinetics and mechanisms of the reactions of these hydridoborate salts with benzhydrylium ions, iminium ions, quinone methides, and Michael acceptors were investigated, and their nucleophilicity was determined and compared with that of other hydride donors.
    Angewandte Chemie International Edition 10/2015; DOI:10.1002/anie.201507298 · 11.26 Impact Factor
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    ABSTRACT: The crystal structures of 1,2-diiodoolefins are governed by extensive halogen bonding involving I...I, I...O and I...C interactions. These interactions are discussed considering nine new crystal structures determined in our laboratory and several additional crystal structures from the literature that complement our data.
    New Journal of Chemistry 09/2015; 39(11). DOI:10.1039/c5nj00821b · 3.09 Impact Factor
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    ABSTRACT: Astellatol and nitidasin belong to a subset of sesterterpenoids that share a sterically encumbered trans-hydrindane motif with an isopropyl substituent. In addition, these natural products feature intriguing polycyclic ring systems, posing significant challenges for chemical synthesis. Herein, the evolution of our stereoselective strategy for isopropyl trans-hydrindane sesterterpenoids is detailed. These endeavors included the synthesis of several building blocks, enabling studies toward all molecules of this terpenoid subclass, and of advanced intermediates of our initial route toward a biomimetic synthesis of astellatol. These findings provided the basis for a second-generation and a third-generation approach toward astellatol that eventually culminated in the enantioselective total synthesis of (-)-nitidasin. In particular, a series of substrate-controlled transformations to install the ten stereogenic centers of the target molecule was orchestrated and the carbocyclic backbone was forged in a convergent fashion. Furthermore, the progress toward the synthesis of astellatol is disclosed and insights into some observed yet unexpected diastereoselectivities by detailed quantum-mechanical calculations are provided. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Chemistry - A European Journal 08/2015; 21(39). DOI:10.1002/chem.201501423 · 5.73 Impact Factor
  • T.J. Kimbrough · P.A. Roethle · P. Mayer · D. Trauner ·

  • Elsa Follet · Guillaume Berionni · Peter Mayer · Herbert Mayr ·
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    ABSTRACT: Eight substituted aryl(indol-3-yl)methylium tetrafluoroborates 3(a-h)-BF4 and three bis(indol-3-yl)methylium tetrafluoroborates 3(i-k)-BF4 have been synthesized and characterized by NMR spectroscopy and X-ray crystallography. Their reactions with π-nucleophiles 8(a-j) (silylated enol ethers, and ketene acetals) were studied kinetically using photometric monitoring at 20 °C. The resulting second-order rate constants were found to follow the correlation log k (20 °C) = sN(N + E), in which nucleophiles are characterized by the two solvent-dependent parameters N and sN, and electrophiles are characterized by one parameter, E. From the previously reported N and sN parameters of the employed nucleophiles, and the measured rate constants, the electrophilicities of the indol-3-ylmethylium ions 3(a-k) were derived and used to predict potential nucleophilic reaction partners. A discrepancy between published rate constants for the reactions of morpholine and piperidine with the (2-methylindol-3-yl)phenylmethylium ion 3h and that calculated from E, N and sN was analyzed and demonstrated to be due to a mistake of the value reported in the literature.
    The Journal of Organic Chemistry 07/2015; 80(17). DOI:10.1021/acs.joc.5b01298 · 4.72 Impact Factor
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    ABSTRACT: A convenient synthesis of cyclometalated complexes [{Rh(μ-Cl)(C N)2}2] [C N = ppy, 2-phenylpyridinato (2); C N = ptpy, 2-(p-tolyl)pyridinato (3); 4-Clppy = 4-chloro-2-phenylpyridinato (4)] at room temperature is described. The compounds were obtained by the oxidative addition reaction of the corresponding 2-phenylpyridines to [{Rh(μ-Cl)(coe)2}2] (1) (coe = cis-cyclooctene) in dichloromethane solution. The rate of the reaction seems to depend on the electronic influence of the substituents on the phenyl rings of the corresponding 2-phenylpyridines. The analogous iridium complex of 1 reacted markedly only at higher temperatures in suitable solvents under cyclometalation. The molecular structure of the new compound 4 was additionally confirmed by an X-ray diffraction study.
    Zeitschrift für anorganische Chemie 07/2015; 641(11). DOI:10.1002/zaac.201500527 · 1.16 Impact Factor
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    ABSTRACT: Aryl sulfonamides are a widely used drug class for the inhibition of carbonic anhydrases. In the context of our program of photochromic pharmacophores we were interested in the exploration of azobenzene-containing sulfonamides to block the catalytic activity of human carbonic anhydrase II (hCAII). Herein, we report the synthesis and in vitro evaluation of a small library of nine photochromic sulfonamides towards hCAII. All molecules are azobenzene-4-sulfonamides, which are substituted by different functional groups in the 4´-position and were characterized by X-ray crystallography. We aimed to investigate the influence of electron-donating or electron-withdrawing substituents on the inhibitory constant K i. With the aid of an hCAII crystal structure bound to one of the synthesized azobenzenes, we found that the electronic structure does not strongly affect inhibition. Taken together, all compounds are strong blockers of hCAII with K i = 25-65 nM that are potentially photochromic and thus combine studies from chemical synthesis, crystallography and enzyme kinetics.
    Beilstein Journal of Organic Chemistry 07/2015; 11:1129-35. DOI:10.3762/bjoc.11.127 · 2.76 Impact Factor
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    ABSTRACT: In the crystal, molecules of the centrosymmetric title compound, C 12 H 4 Br 2 F 4 N 2 , are linked into strands along [011] by weak C—H...F contacts. Furthermore, the molecules are π–π stacked with perpendicular ring distances of 3.4530 (9) Å.
    07/2015; 71(7):o459-o460. DOI:10.1107/S2056989015010622
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    ABSTRACT: Reaction of [{Ir(μ-Cl)(coe)2}2] (1; coe = cis-cyclooctene) with 4 equiv. of PtBu2Ph in CH2Cl2 at ambient temperature resulted in oxidative addition of one phosphane ligand affording the known cyclometalated IrIII complex [IrCl(H)(PtBu2C6H4-κ2P,C)(PtBu2Ph)] (2) in high yield. Compound 2 exhibits a coordinatively unsaturated five-coordinate 16 VE species, and its reactivity towards strong π-acceptor ligands is investigated. Reaction of 2 with CO resulted in addition of the CO ligand and inversion of cyclometalation to give known IrI complex trans-[IrCl(CO)(PtBu2Ph)2] (3). In a similar manner, 1 reacted with nitrosonium tetrafluoridoborate affording the new complex salt [IrCl(NO)(PtBu2Ph)2][BF4] (4), which is isoelectronic with 3. Compounds 2 and 4 were characterized by spectroscopic methods as well as by X-ray crystallography confirming their molecular structures.
    Berichte der deutschen chemischen Gesellschaft 06/2015; 2015(20). DOI:10.1002/ejic.201500363 · 2.94 Impact Factor
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    Elaheh Ahadi · Hassan Hosseini-Monfared · Peter Mayer ·
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    ABSTRACT: In the title compound, [CuCl2(C7H7NO2)2], the square-planar-coordinated CuII ion lies on a centre of symmetry and is bonded to two monodentate methyl­isonicotinate ligands through their N atoms and by two chloride ligands. The mol­ecules pack in a herringbone pattern. Perpendicular to [100] there are weak inter­molecular C-HCl and C-HO contacts. Along [100] there are infinite chains of edge-sharing octa­hedra linked through the chlorido ligands
    05/2015; 71(5):m112-m113. DOI:10.1107/S205698901500729X
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    ABSTRACT: Two new Cu(II) complexes were synthesized from Cu(NO 3) 2 Á3H 2 O and salan ligands, H 2 [H 4 ]L 1 and H 2 [H 4 ]L 2 (H 2 [H 4 ]L 1 = N,N 0 -bis(o-hydroxybenzyl)-1,2-diaminocyclohexane; H 2 [H 4 ]L 2 = N,N 0 -bis(o-hydroxybro-mobenzyl)1,2-diaminocyclohexane). They were character-ized by various spectroscopic methods and structures of the complexes determined by X-ray diffraction analyses. Interestingly, H 2 [H 4 ]L 1 coordinates to copper centers as monoanionic in a tetradentate mode in complex 1, [Cu(H[H 4 ]L 1)] 2 Á2NO 3 Á2H 2 O, whereas H 2 [H 4 ]L 2 behaves as a dianionic ligand in complex 2, [Cu([H 4 ]L 2)] 2 Á0.4H 2 O, via the O,N,N 0 ,O 0 -donor atoms. The asymmetric unit in the complexes is dimerized about a center of inversion by asymmetric bridging of the phenoxide-O atom between two metal centers. The electronic spectra studies of the complexes in various solvents with different coordination numbers proved the stability of the dinuclear complexes in solvents other than DMSO and DMF. Complexes 1 and 2 showed high catalytic activities with good-to-excellent selectivities in the oxidation of olefins, benzyl alcohol and ethyl benzene with H 2 O 2 in acetonitrile. A probable mechanism is discussed.
    Transition Metal Chemistry 02/2015; · 1.31 Impact Factor
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    ABSTRACT: Two new Cu(II) complexes were synthesized from Cu(NO3)2·3H2O and salan ligands, H2[H4]L1 and H2[H4]L2 (H2[H4]L1 = N,N′-bis(o-hydroxybenzyl)-1,2-diaminocyclohexane; H2[H4]L2 = N,N′-bis(o-hydroxybromobenzyl)1,2-diaminocyclohexane). They were characterized by various spectroscopic methods and structures of the complexes determined by X-ray diffraction analyses. Interestingly, H2[H4]L1 coordinates to copper centers as monoanionic in a tetradentate mode in complex 1, [Cu(H[H4]L1)]2·2NO3·2H2O, whereas H2[H4]L2 behaves as a dianionic ligand in complex 2, [Cu([H4]L2)]2·0.4H2O, via the O,N,N′,O′-donor atoms. The asymmetric unit in the complexes is dimerized about a center of inversion by asymmetric bridging of the phenoxide-O atom between two metal centers. The electronic spectra studies of the complexes in various solvents with different coordination numbers proved the stability of the dinuclear complexes in solvents other than DMSO and DMF. Complexes 1 and 2 showed high catalytic activities with good-to-excellent selectivities in the oxidation of olefins, benzyl alcohol and ethyl benzene with H2O2 in acetonitrile. A probable mechanism is discussed.
    Transition Metal Chemistry 02/2015; 40(3). DOI:10.1007/s11243-015-9913-6 · 1.31 Impact Factor

  • ChemInform 02/2015; 46(6):no-no. DOI:10.1002/chin.201506230
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    ABSTRACT: Aus Thienyl- bzw. Furylboronsäureestern und Aryllithium-Verbindungen hergestellte Bor-at-Komplexe wurden isoliert und durch Röntgenstrukturanalyse charakterisiert. Die Produkte und Mechanismen ihrer Reaktionen mit Carbenium- und Iminium-Ionen wurden analysiert. Durch UV/Vis-spektroskopische Verfolgung der Kinetik dieser Reaktionen wurde der Einfluss der Aryl-Substituenten, der Diol-Liganden (Pinakol, Ethylenglykol, Neopentylglykol, Brenzkatechin) und der Gegenionen auf die nucleophile Reaktivität der Bor-at-Komplexe untersucht. Eine Hammett-Korrelation bestätigte die polare Natur ihrer Reaktionen mit Benzhydrylium-Ionen, und die Korrelation lg k(20 °C)=sN(E+N) wurde verwendet, um die Nucleophilie der Bor-at-Komplexe zu bestimmen und mit der anderer Borate und Boronate zu vergleichen. Die Neopentylglykol- und Ethylenglykol-Derivate sind 104-mal reaktiver als die Pinakol- und Brenzkatechin-Derivate.
    Angewandte Chemie 01/2015; 127(9). DOI:10.1002/ange.201410562
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    ABSTRACT: Boron ate complexes derived from thienyl and furyl boronic esters and aryllithium compounds have been isolated and characterized by X-ray crystallography. Products and mechanisms of their reactions with carbenium and iminium ions have been analyzed. Kinetics of these reactions were monitored by UV/Vis spectroscopy, and the influence of the aryl substituents, the diol ligands (pinacol, ethylene glycol, neopentyl glycol, catechol), and the counterions on the nucleophilic reactivity of the boron ate complexes were examined. A Hammett correlation confirmed the polar nature of their reactions with benzhydrylium ions, and the correlation lg k(20 °C)=sN(E+N) was employed to determine the nucleophilicities of the boron ate complexes and to compare them with those of other borates and boronates. The neopentyl and ethylene glycol derivatives were found to be 104 times more reactive than the pinacol and catechol derivatives.
    Angewandte Chemie International Edition 01/2015; 54(9). DOI:10.1002/anie.201410562 · 11.26 Impact Factor
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    ABSTRACT: The ambient pressure phase of silicon disulfide (NP-SiS 2), published in 1935, is orthorhombic and contains chains of distorted, edge-sharing SiS 4 tetrahedra. The first high pressure phase, HP3-SiS 2 , published in 1965 and quenchable to ambient conditions, is tetragonal and contains distorted corner-sharing SiS 4 tetrahedra. Here, we report on the crystal structures of two monoclinic phases, HP1-SiS 2 and HP2-SiS 2 , which can be considered as missing links between the orthorhombic and the tetragonal phase. Both monoclinic phases contain edge-as well as corner-sharing SiS 4 tetrahedra. With increasing pressure, the volume contraction (−ΔV/V) and the density, compared to the orthorhombic NP-phase, increase from only edge-sharing tetrahedra to only corner-sharing tetrahedra. The lattice and the positional parameters of NP-SiS 2 , HP1-SiS 2 , HP2-SiS 2 , and HP3-SiS 2 were derived in good agreement with the experimental data from group−subgroup relationships with the CaF 2 structure as aristotype. In addition, the Raman spectra of SiS 2 show that the most intense bands of the new phases HP1-SiS 2 and HP2-SiS 2 (408 and 404 cm −1 , respectively) lie between those of NP-SiS 2 (434 cm −1) and HP3-SiS 2 (324 cm −1). Density functional theory (DFT) calculations confirm these observations.
    Inorganic Chemistry 01/2015; 54(4). DOI:10.1021/ic501825r · 4.76 Impact Factor
  • Martin Olbrich · Peter Mayer · Dirk Trauner ·
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    ABSTRACT: A synthetic strategy toward the intriguing hydrocarbon nanorod polytwistane is outlined. Our approach aims toward the polymerization of acetylene starting from precursors that would provide a helical bias for the formation of polytwistane. Both transition metal catalyzed and radical polymerizations were investigated. Two potential initiator molecules were synthesized that could be used for either approach. Although the intended regioselectivities were not observed, unusual organopalladium complexes and numerous compounds with novel carbon skeletons were obtained.
    The Journal of Organic Chemistry 12/2014; 80(4). DOI:10.1021/jo502618g · 4.72 Impact Factor
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    ABSTRACT: A new Mn(II) coordination polymer, [Mn (L1)2(NCS)2]n (1) [L1=3,4-bis(4-pyridyl)-5-(2-pyridyl)-1,2,4-triazole] was synthesized by the reaction of ligand L1 and mixtures of manganese(II) acetate and potassium thiocyanate using the heat gradient method. Compound 1 has been characterized by IR spectroscopy, elemental analyses and X-ray crystallography. The crystal structure of compound 1 was determined by single-crystal X-ray diffraction and shows a new interesting one-dimensional coordination polymer. Nanostructures of compound 1 have been synthesized by sonochemical method. The products were characterized by X-ray powder diffraction, scanning electron microscopy (SEM), and IR spectroscopy. The thermal stability of nano particles of compound 1 was studied by thermal gravimetric and differential thermal analyses. Copyright © 2014 Elsevier B.V. All rights reserved.
    Ultrasonics Sonochemistry 11/2014; 24. DOI:10.1016/j.ultsonch.2014.11.011 · 4.32 Impact Factor

Publication Stats

5k Citations
1,253.12 Total Impact Points


  • 2001-2015
    • Ludwig-Maximilians-University of Munich
      • • Department of Chemistry
      • • Faculty of Chemistry and Pharmacy
      • • Department of Biochemistry
      München, Bavaria, Germany
  • 2001-2014
    • Technische Universität München
      • Department of Biochemistry
      München, Bavaria, Germany
  • 2000-2014
    • University Hospital München
      München, Bavaria, Germany
  • 2007
    • University of Rostock
      • Inorganic Chemistry
      Rostock, Mecklenburg-Vorpommern, Germany
  • 2005
    • Nelson Mandela Metropolitan University
      • Department of Chemistry
      Port Elizabeth, Eastern Cape, South Africa