Characterisation of Alkane σ-Complexes

Alkane sigma-complexes have evolved from a curious phenomenon to an intermediate of intense interest, fuelling research into the area. Over the last fifteen years, metal alkane complex characterisation has evolved to incorporate reports employing UV/Vis, IR and NMR spectroscopy, and Xray and neutron diffractometry. Previously, due to the sparse geometric characterisation of alkane sigma-complexes, assumptions regarding bonding geometries and selectivities were made by comparison to related sigma-complexes, or by analysis of C-H activation products. This minireview assembles relevant literature that illuminates the metrics of alkane-metal bonding, and critically analyses the binding mode, selectivity and stability of alkane complexes.