Facile and Regioselective C–H Bond Activation of Aromatic Substrates by an Fe(II) Complex Involving a Spin-Forbidden Pathway

The Fe­(II) complex Cp*Fe­(CO)­(NCMe)­Ph (Cp* = η⁵-pentamethylcyclopentadienyl) is shown to mediate facile and highly regioselective C–H activation of aromatic substrates including benzene, furan, thiophene, thiazole, and 2-methylfuran. Experimental and computational evidence suggest a mechanism for C–H activation that involves NCMe dissociation, multiple spin intersystem crossings, C–H bond coordination, and C–H bond cleavage by a σ-bond metathesis reaction.