Vorträge-Koll

Catalytic Syntheses of Five-membered Cyclic Compounds via -Unsaturated Early Transition Metal Alkylidene Intermediates Cyclopentadienes and pyrroles are synthetically valuable five-membered cyclic compounds. Transition metal-catalyzed [2+2+1]-cycloaddition reactions involving two simple alkynes and a carbene or nitrene precursor offer an efficient and atom-economical route to these compounds. However, the scope of suitable carbene and nitrene precursors remains limited in such catalytic transformations. In this presentation, I will introduce our strategy employing cyclopropenes and azoarenes as novel substrates for unprecedented [2+2+1]-cycloaddition reactions with alkynes. These reactions are catalyzed by low-valent early transition metal complexes such as niobium and tungsten, and proceed via key intermediates featuring β-unsaturated metal alkylidene species.

Prof. Dr. Prince Ravat, Prof. Dr. Oliver Dumele, Universität zu Köln Twisting Light and Spin: Helicenes as Multifunctional Molecular Spring Helicenes, with their characteristic corkscrew-shaped geometry, serve as versatile molecular scaffolds for constructing configurationally robust chiral functional materials through precise structural design. Ravat group focuses on leveraging this unique architecture to control electronic and (chir)optical properties at the molecular level. Dumele group has employed helicenes as building blocks for two-dimensional covalent organic frameworks (COFs), uncovering their crystalline order arising from homochiral (enantiopure) or racemic packing modes. This work has led to an unexpected discovery — the same [5]helicene can act as a photochemical spin-state switch, enabling reversible control of the magnetism with light.

Junge Forscherinnen und Forscher der Bonner Chemie stellen sich vor Anschließend: Snacks und Getränke mit dem JCF Bonn

There has been great interest in compounds with double bonds between heavier group 15 elements due to their unusual properties. We achieved the synthesis and characterization of the first stable distibene (ArSb=SbAr) and dibismuthene (ArBi=BiAr) using bulky Tbt and Bbt groups. The cyclic voltammograms of dipnictenes (1b–3b) revealed reversible one-electron reductions, with distibene showing the lowest reduction potential. The anion radical species of 1b and 2b were synthesized and isolated as stable crystalline compounds via Li reduction, and the distibene radical (2b) was structurally confirmed by X-ray analysis. These π-bond systems of heavier group 15 elements display remarkable redox behavior. Furthermore, 1,2-bis(ferrocenyl)dipnictenes (4–6) were synthesized as novel bimetallic d–π electron systems. Recent advances in low-coordinated heavier group 15 species will be discussed.

Prof. Dr. Eva Hevia, Universität Bern Titel wird noch bekannt gegeben Anschließend: GDCh-Preisverleihung