Hydrindacene-based Carbene-Analogues

• Applicant: Professor Dr. Jens Beckmann
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576846305

The kinetic stabilization of reactive species relies on the judicious choice of bulky and rigid substituents. We recently demonstrated that hydrindacene-based so-called MSFluind-substituents are capable to stabilize carbene analogues of group 15, namely the phosphenium ions, [MSFlunidPR]+ (R = Ph, Mes), and the nitrene, MSFluindN, both possessing an electron sextet and non-bonding electrons. Owing to the high symmetry and two degenerate p-orbitals, MSFluindN exists in an electronic triplet ground state and shows macroscopic paramagnetism. The MSFluindN is stable for at least three days at room temperature and exceeds the typical life span of other arylnitrenes in the nanosecond range by a factor of 100 trillion. This extraordinary extension of the life time enables systematic reactivity studies of triplet nitrenes for the first time. In the first part of the project, we aim to study the redox chemistry of MSFluindN, its reactivity towards small molecules and its use as ligand for transition metal complexes. Of particular interest is the synthesis of currently unknown stable nitrenium ions, [MSFlunidNR]+, which are heavier analogues of phosphenium ions, [MSFlunidPR]+. In the second part of the project, we wish to extend this chemistry into group 16. The (electro-)chemical oxidation of diarylchalcogenides, MSFluindER (E = S, Se, Te), should afford radical cations, [MSFluindER]‧+, and dications, [MSFluindER]2+, comprising electron septets and sextets, respectively. In a similar manner, the (electro-)chemical oxidation of arylchalcogenyl halides, MSFluindEX (E = S, Se, Te; X = Cl, Br, I), should yield radical cations, [MSFluindEX]‧+. On the other hand, the halide abstraction of MSFluindEX, should give rise to the formation of arylchalcogenyl ions [MSFluindE]+ having an electron sextet and most likely an electronic triplet ground state, like the isoelectronic nitrene MSFluindN. Finally, we would like to investigate the (electro-)chemical oxidation of diaryltrichalcogenides, (MSFluindE)2E' (E, E' = S, Se, Te), with the expectation to generate radical cations [(MSFluindE)2E']‧+, possibly with spin density being delocalized over the three chalcogens.

• DFG Programme: Research Grants