Inner-sphere electron transfer in metal-cation chemistry

Bond activation of organic molecules by metal cations is usually rationalized either in terms of the chemistry of Lewis acids or via oxidative addition of metal fragments to R---X bonds, that is, R---X+M⁺→R---M⁺---X→products. In most of these mechanisms, the positive charge is assumed to be located on the metal center. Here, we propose an alternative mechanism, to which we refer as inner-sphere electron transfer (ET). Thus, provided that certain conditions are fulfilled, the insertion species R---M⁺---X may isomerize via ET to [ R⁺ MX] structures with the positive charge located mostly at the organic residue R. If R---M⁺---X and [ R⁺ MX] are not just resonance structures but distinct minima on the related potential-energy surfaces, there also exists a transition structure between the two, that is, an ET-TS. Here, the role of inner sphere ET in organometallic gas-phase reactions and the possible existence of ET-TSs are discussed for a series of examples investigated both computationally and experimentally.     

On symmetric gauge fields

The subgroups of the symmetry group of the gauge invariant Lagrangian are studied. For given subgroupG theG-invariant gauge fields are listed.     

1,3-Dioxolanylium- und 1,3-Dioxanylium-Derivate via Protonenkatalysierte SNi-Reaktionen in der Gasphase

By means of chemical ionization 1,3-dioxolanylium as well as 1,3-dioxanylium ions are formed in proton catalysed S_Ni assisted heterolysis in the gas phase. The effects of both constitution and configuration are discussed and compared with the results of analogous reactions in the condensed phase. It is shown that the unimolecular decompositions of [MH]⁺ ions containing two vicinal substituents, e.g. Br or OAc, are not governed by the proton affinity of the departing neutrals HBr or HOAc, respectively. The findings partially contradict the results on HX loss (X: substituent) from protonated monosubstituted compounds.     

Eine katalytisch-kinetische strömungsmethode auf papier. Die bestimmung von molybdän

A new catalytic-kinetic flow method is described, in which a capillary support, filter paper, serves as medium for the reaction as well as for the transport. The catalyst to be determined and the two reactants migrate through a filter paper strip. On a suitable place of the filter paper itself, the concentration of one of the reactants is continuously measured. The example of the molybdenum catalyzed reaction between hydrogen peroxide and iodide illustrates the procedure. The course of the reaction is followed potentiometrically with an iodide-selective electrode.