Promoting Alkane Binding: Crystallization of a Cationic Manganese(I)‐Pentane <i>σ</i> ‐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 noncoordinating solvent environment to [Mn(CO)₅]⁺ 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)]⁺ crystallize from solution at room temperature and their structures were determined by single crystal X-ray crystallography. The oxidation of metal complex dimers in solution to generate reactive metal cations, which bind alkanes as the strongest available ligand, is a new and probably general approach to generate metal-alkane σ-complexes.