Photo-Chlorination of Linear Alkanes with 2-Position Selectivity Using a Metal-Organic Layer Catalyst

Controlling regioselectivity in activating C−H bonds in linear alkanes is challenging, as their multiple secondary C−H bonds have quite similar dissociation energies with no functional groups to differentiate between the bonds. Amidyl radicals generated from N‒halogen amides were reported to activate C−H bonds with an interesting 2-position selectivity. Here, with a possibility to access the amidyl radical photocatalytically, we coupled ligand-to-metal charge transfer (LMCT)-based radical generation and amide functional group on a tailor-designed metal-organic layer (MOL) material. We achieved efficient photo-chlorination of linear alkanes with 2-position selectivity. For example, with n-hexane as the substrate, 2-chloro-n-hexane was obtained with 85% selectivity and a turnover number of 2200 in 8 hours, together with a high apparent quantum yield of ~7% at room temperature. Transient absorption spectroscopy reveals that a FeIV species is involved in the initial photo-driven process that possibly oxidizes the amide center to an amidyl radical.