Conditions that Promote Alkane Binding: Crystallization of a Cationic Manganese(I) Pentane σ-Complex from Solution

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. Here we present a synthetic methodology that converts Mn2(CO)10 in a non-coordinating solvent environment to [Mn(CO)5]+ at room temperature, which binds n-pentane as the strongest interacting ligand available. Three isomers of its σ complexes were studied in detail by solution NMR-spectroscopy at low temperature. Two isomers of [Mn(CO)5(n-pentane)]+ crystallize from solution at room temperature and their structures were determined by single crystal X-ray crystallography. Hence, we suggest that the solution oxidation of metal complex dimers to generate reactive metal cations, which bind alkanes as the strongest available ligand, is a new and general approach for the generation of metal-alkane σ complexes.