Der austausch des cyclopentadienylliganden im methylcyclopentadienyl-mangantricarbonyl : Darstellung und zusammensetzung der komplexe mit methyl-substituierten benzolen

The exchange of the cyclopentadienyl ring in methylcyclopentadienylmanganese(I) tricarbonyl by methy-substituted benzenes in the presence of aluminium halide leads to [arene-Mn(CO)₃]⁺-ions. The reaction conditions have been optimised; in addition to the yield the purity of the complexes has been determined in some detail. After mild decomposition the arenes were analysed by GLC. Pure [arene-Mn(CO)₃]⁺-ions can be isolated with benzene, toluene, m- and o-xylene.     

Traceability study of hay with a mass spectrometer based on ion-molecule reactions of krypton,xenon and mercury using multivariate data analysis

The application of mountain hay for wellness purposes has led to a substantial valorisation. To assure the quality associated with the high standards of production, which are often related to a characteristic distribution of plants and a variety of essential oils, a mass spectrometer, based on ion-molecule-reactions (IMR) of mercury, krypton and xenon, was employed to analyse characteristic VOCs of hay such as coumarin or typical monoterpenes and then used to develop an approach for the traceability of single hay samples based on concepts of multivariate statistics. The application of the primary gases to aqueous solutions of the pure compounds shows their suitability to deal with this problem, reveals important factors for the creation of a measurement set-up of such gas mixtures and indicates different mechanisms for the fragmentation, as shown for coumarin. The limit of determination (3*s_R/SEN) for aqueous solutions of p-cymene is 0.13?mg?L^?1 using PLS1 and the presented combined mercury and xenon set-up, which confirms that this strategy is appropriate for an integration of compounds, which are present in low concentrations only, into a qualitative model. The results of the principal component analyses (PCA) of 136 hay samples were verified for the suitability to characterize single types of hay using three measurements of nine mountain hay samples, three normal hay samples and three aftermath samples for evaluation and applying SIMCA for classification at a significance level of 5%. The traceability of mountain hay samples is good (93% correctly classified) and can be used to protect these valuable samples.     

Cu(I)-carbenoid- and Ag(I)-Lewis acid-catalyzed asymmetric intermolecular insertion of alpha-diazo compounds into N-H bonds

Chiral Cu(I)-bisoxazoline- and Cu(I)-PN-complexes were found to catalyze the intermolecular insertion of alpha-diazo compounds into N-H bonds. The insertion reactions proceed with enantioselectivities of up to 28% ee for the different alpha-diazo acetates into one of the N-H bonds of different amines. Analogous chiral Ag(I) complexes were found to give higher enantioselectivities of up to 48% ee, however, lower yields were obtained. There are indications, that the Ag(I)-mediated reactions follow a different reaction mechanism compared to the Cu(I)-catalyzed insertions. It is demonstrated that different alpha-amino acid derivatives can be obtained via this approach in good yields and with low to moderate enantioselectivities. However, the results obtained are the highest asymmetric inductions obtained for an intermolecular N-H insertion via chiral carbene complexes or chiral Lewis acid catalysis.     

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