A General Route to Metal-Alkane σ-Complexes in Solution and the Solid State

• Applicant: Professor Dr. Ingo Krossing
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576425151

Transition metal–alkane σ-complexes are key intermediates in C–H activation and, until now, analysis of these species has been restricted to either the solution or the solid state. Very recently, we presented a synthetic methodology that converts Mn2(CO)10 in a non-coordinating solvent environment to the [Mn(CO)5]+ intermediate at room temperature, and this species binds n-pentane as the strongest interacting ligand available. Three isomers of the n-pentane σ complexes were studied in detail by solution NMR-spectroscopy at low temperature. Two isomers of [Mn(CO)5(n-pentane)]+ crystallized from solu¬tion at room temperature and their structures were de¬termined by single crystal X-ray crystallography (scXRD). With this proposal we aim at the solution oxidation of metal complex dimers M2(L)2n like Re2(CO)10, or M2(Cp)2(CO)4 (M = Fe, Ru, Os) with selective deelectronators sD+ like [C10F8]+·[WCA]– (WCA = Al(ORF)4, HCB11F11) to ge¬ne¬rate reactive metal cations [(◻)M(L)n]+, which bind al¬kanes as the stron¬gest available ligand to give the desired [(Alkane)M(L)n]+[WCA]– salts, and wish to establish this route as a new and general approach to generate and fully characterize and mechanistically study such elusive metal-alkane σ com¬plexes. In four Work Packages (WPs) we aim at “Increasing Alkane Substrate Scope of the [Mn(CO)5]+ Intermediate” (WP 1), at “Increasing the Acceptor Scope for Cationic Metal Alkane σ Complexes” (WP 2), “Towards stable Methane σ Complexes ” (WP 3) and “Orienting Work towards further Transformations of Metal Alkane σ Complexes” (WP 4).

• DFG Programme: Research Grants
• International Connection: Australia
• Cooperation Partners: Professor Dr. Graham Ball; Professor Dr. Les Field