Mathias Lehmann

University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany

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Publications (12)47.91 Total impact

  • Mathias Lehmann, Axel Schulz, Alexander Villinger
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    ABSTRACT: Positiv Denken – Haltet die Anionen fern! Bis dato unbekannte Mono‐ und Dikationen des Typs [XE(μ‐NTerE)]+ und [E2(μ‐NTer)2]2+ (E=Sb, Bi; X=Cl, I) wurden untersucht und vollständig charakterisiert. Salze mit diesen hochreaktiven Kationen erhält man ausgehend von Terphenyl‐substituierten cyclo‐Dipniktadiazanen [XE(μ‐NR)]2 durch Halogenidabstraktion oder Triflatsubstitution.
    Angewandte Chemie 08/2012; 124(32).
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    ABSTRACT: The Lewis acid assisted triflate/methyl, azide/methyl, and chlorine/methyl exchange reactions between silicon and antimony have been studied in the reaction of R(Me(3)Si)N-SbCl(2) (R = Ter) with AgOTf, AgN(3), KOtBu, GaCl(3), and Me(3)SiN(3)/GaCl(3), resulting in the formation of different methylantimony compounds. Furthermore, R(Me(3)Si)N-SbCl(2) (R = SiMe(3)) was reacted with GaCl(3) at low temperatures to yield a hitherto unreported amino(chloro)stibenium cation, the proposed intermediate in methyl exchange reactions. Tetrachloridogallate salts bearing different stibinostibonium cations such as [(Me(3)Sb)SbMe(2)](+) and [(Me(3)Sb)(2)SbMe](2+) along with the GaCl(3) adduct of SbMe(3) were isolated from such R(Me(3)Si)N-SbCl(2)/GaCl(3) mixtures (R = SiMe(3)) at ambient temperatures, depending on the reaction parameters.
    Inorganic Chemistry 07/2012; 51(15):8212-24. · 4.59 Impact Factor
  • Mathias Lehmann, Axel Schulz, Alexander Villinger
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    ABSTRACT: Think positive, keep the anions away: Hitherto unknown mono- and dications of the type [XE(μ-NTerE)](+) and [E(2) (μ-NTer)(2) ](2+) (E=Sb, Bi; X=Cl, I) were studied and fully characterized for the first time. Salts bearing these highly reactive cations can be obtained from terphenyl-substituted cyclo-dipnictadiazanes [XE(μ-NR)](2) by halide abstraction or triflate substitution.
    Angewandte Chemie International Edition 07/2012; 51(32):8087-91. · 11.34 Impact Factor
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    ABSTRACT: The reaction of AgC(6)F(5) with monomeric iminophosphanes of Mes*-N═P-X (X = Cl, I) in CH(2)Cl(2) at ambient temperature gives imino(pentafluorophenyl)phosphane, Mes*N═P(C(6)F(5)) (1), in almost quantitative yield (96%), which could be isolated as a highly viscous blue oil. The same reaction with LiC(6)F(5) results in the formation of imino(amino)phosphane (C(6)F(5))(2)P-N(Mes*)-P═NMes* (2) (yield 93%). In the second series of experiments the analogous reaction of MC(6)F(5) (M = Ag, Li) with dimeric [Cl-P(μ-N-Dipp)](2) was studied, leading to the formation of [R-P(μ-N-Dipp)](2) (R = C(6)F(5)) (3) for M = Ag, while only decomposition products such as P(C(6)F(5))(3) were observed in the reaction with the Li salt. Highly labile Mes*-N═P-C(6)F(5) (1) decomposes at ambient temperatures, forming among other products the diphosphane (C(6)F(5))(2)P-P(C(6)F(5))(2) (4). Reaction of 1 with Fe(2)(CO)(9) yields the iron carbonyl complexes Mes*-N═P(C(6)F(5))·Fe(CO)(4) (5) and [Mes*-N═P(C(6)F(5))](2)·Fe(CO)(3) (6). The structure, bonding, and potential energy surface are discussed on the basis of B3LYP/6-31G(d,p) computations. According to time-dependent B3LYP calculations, the blue color of 1 arises from an n → π* electronic transition.
    Inorganic Chemistry 06/2011; 50(12):5784-92. · 4.59 Impact Factor
  • Mathias Lehmann, Axel Schulz, Alexander Villinger
    Angewandte Chemie International Edition 05/2011; 50(22):5221-4. · 11.34 Impact Factor
  • Mathias Lehmann, Axel Schulz, Alexander Villinger
    Angewandte Chemie 05/2011; 123(22).
  • Mathias Lehmann, Axel Schulz, Alexander Villinger
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    ABSTRACT: The monomer/dimer equilibrium has been studied for a series of alkyl and aryl substituted and functionalized iminochlorophosphane species of the type R–N=P–Cl. In agreement with experiment, theoretical data always favor the dimer when the group R is small, while bulky groups such as Mes* destabilize the dimer by a considerable steric repulsion. This effect is superimposed by electronic effects. Para-substitution in the aryl systems either favors the monomer (energy gain ca. 15–30 kJ/mol) when a π-electron donating group such as p-NMe2 is used or favors the dimer when a π-electron withdrawing group such as p-NO2 is used (energy gain ca. 1–13 kJ/mol).
    Structural Chemistry 01/2011; 22(1):35-43. · 1.77 Impact Factor
  • Mathias Lehmann, Axel Schulz, Alexander Villinger
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    ABSTRACT: The whole series of four-membered rings of the type [X–Sb(μ-NR)]2, containing alternating antimony(III) and nitrogen centers, have been synthesized and fully characterized (X = halogen, R = supermesityl = 2,4,6-tri-tert-butylphenyl = Mes*) and represent rare examples of cyclo-distiba-diazanes. The synthesis was carried out starting from the triflate species [TfO–Sb(μ-NR)]2, which has been generated by utilizing a new synthetic route. By Me3Si–OTf elimination, reactions of [TfO–Sb(μ-NR)]2 with Me3Si–X yielded the halogen compounds [X–Sb(μ-NR)]2 with the exception of the fluorine species for which an iodine/fluorine exchange reaction with AgF was successfully applied. The structures of all starting materials, along the reaction pathway, and of all halogen species were determined by single-crystal X-ray diffraction. While for the compounds [X–Sb(μ-NR)]2 (X = OTf, Cl, Br, and I), a molecular structure with no significant intermolecular interactions was observed, the analogous fluorine species[F–Sb(μ-NR)]2 displays Sb···F van der Waals interactions between the centrosymmetric dimers, which leads to a chain-like structure in the crystal.
    Berichte der deutschen chemischen Gesellschaft 12/2010; 2010(35). · 2.94 Impact Factor
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    ABSTRACT: The synthesis and structure of lithium and silver tetrakis(pentafluorophenyl)borate salts have been studied in different solvents ranging from polar (CH2Cl2, diethyl ether) to nonpolar (toluene, pentane). While Li[B(C6F5)4] is stable in all studied solvents and crystallizes with four ether molecules from ether and with two toluene molecules from toluene, the silver salt is only stable when the Ag+ ion is strongly coordinated such as in [Ag(toluene)3][B(C6F5)4] or [Ag(Et2O)3][B(C6F5)4]. In weakly coordinating solvents such as CH2Cl2 Ag[B(C6F5)4] decomposes, yielding AgC6F5 and B(C6F5)3. The overall process of the AgC6F5 synthesis starting from B(C6F5)3 and LiC6F5 can formally be regarded as a B(C6F5)3-catalyzed reaction. The salt [Ag(toluene)3][B(C6F5)4] presents an easily accessible, ether-free, stable silver salt of the [B(C6F5)4]− anion. All compounds have been fully characterized.
    Organometallics. 02/2010; 29(6).
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    ABSTRACT: Treating 1,3-dichloro-2,4-bis[tris(trimethylsilyl)silyl]-cyclo-diphosphadiazane, [HypNPCl]2 ((Me3Si)3Si=Hyp), or N-(2,4,6-tri-tert-butylphenyl)imino(chloro)phosphane, Mes∗–NP–Cl (Mes∗=2,4,6-tri-tert-butylphenyl), with Ag[Al(OCH(CF3)2)4] leads to the abstraction of [OCH(CF3)2]− from the counter ion [Al(OCH(CF3)2)4]− in a formal Lewis acid/Lewis base reaction. The final products Hyp2N2P2(Cl)(OCH(CF3)2), Mes∗–NP–OCH(CF3)2 and the dimeric Lewis acid [Al(OCH(CF3)2)3]2 have been characterized by means of X-ray analysis.
    Journal of Organometallic Chemistry - J ORGANOMET CHEM. 01/2010; 695(7):1006-1011.
  • Mathias Lehmann, Axel Schulz, Alexander Villinger
    Angewandte Chemie International Edition 10/2009; 48(40):7444-7. · 11.34 Impact Factor
  • Mathias Lehmann, Axel Schulz, Alexander Villinger
    Angewandte Chemie 09/2009; 121(40).