Publications (13)57.33 Total impact
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] ABSTRACT: Amino(azido)stibanes Mes*N(SiMe3)Sb(N3)X (X = N3, Cl, OTf) were synthesized and fully characterized. Their structures were determined by single-crystal X-ray diffraction and are rare examples of antimony azides. On account of weak Sb···X van der Waals interactions, centrosymmetric dimers are observed in the solid state. Mes*N(SiMe3)Sb(OTf)X species (X = Cl, N3, and OTf; OTf = triflate = CF3SO3–) are labile with respect to Me3Si–OTf elimination even at ambient temperatures and form in situ the highly reactive iminostibane Mes*N=SbX, which rapidly decomposes. Diazide Mes*N(SiMe3)Sb(N3)2 slowly decomposes when a Lewis acid such as B(C6F5)3 is present, thus leading to the formation of a salt that bears a heterocyclic Sb–N dication and an [N3–B(C6F5)3]– adduct anion in good yields.
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] ABSTRACT: Ein Schutzschild macht es möglich: Die erste Synthese und vollständige Charakterisierung eines Tetrazastibols wird vorgestellt. Die Umwandlung von [N3Sb(μ-NMes*)2SbN3] in das Tetrazastibol Mes*-N4Sb stellt eine ungewöhnliche Isomerisierung dar, die durch die Lewis-Säure B(C6F5)3 ausgelöst wird. Darüber hinaus wird die Lewis-Säure zur Adduktbildung benötigt, wodurch der N4Sb-Ring zwischen dem großen Arylrest und der sperrigen B(C6F5)3-Einheit kinetisch geschützt wird.
- [Show abstract] [Hide abstract] ABSTRACT: A protective shield makes it possible: The synthesis and full characterization of a tetraazastibole is presented for the first time. The conversion of [N 3Sb(μ-NMes*) 2SbN 3] (Mes*=2,4,6-Me 3C 6H 2) into tetraazastibole, Mes*N 4Sb, is an unusual isomerization triggered by the action of the Lewis acid B(C 6F 5) 3, which is also needed for adduct formation: the N 4Sb ring is kinetically protected between the large Mes* and B(C 6F 5) 3 units.
- [Show abstract] [Hide abstract] 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).
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] ABSTRACT: Double duty: The series of salts containing the bissilylated halonium cation [Me3Si-X-SiMe3]+ (X=F, Cl, Br, and I; see picture) has been generated and fully characterized in the super Lewis acidic silylating medium Me3Si X (as solvent and reactant) and [Me3Si][B(C6F5)4] (as silylating reagent).
- [Show abstract] [Hide abstract] ABSTRACT: Mit doppelter Funktion erfolgreich: Alle bissilylierten Haloniumkationen [Me3SiXSiMe3]+ (X=F, Cl, Br, I) wurden in einem super-Lewis-sauren silylierenden Medium synthetisiert und vollständig charakterisiert. Me3SiX fungierte in dieser Reaktion sowohl als Lösungsmittel wie auch als Ausgangsverbindung und wurde durch [Me3Si][B(C6F5)4] silyliert.
University of Rostock
Rostock, Mecklenburg-Vorpommern, Germany
- Inorganic Chemistry