Well-Defined Aryl-Fe II Complexes in Cross-Coupling and C-H Activation Processes.

Herein we explore the intrinsic organometallic reactivity of iron embedded in a tetradentate N 3 C macrocyclic ligand scaffold that allows the stabilization of aryl-Fe species, which are key intermediates in Fe-catalyzed cross-coupling and C-H functionalization processes. This study covers C-H activation reactions using Me L H and FeCl 2 , biaryl C-C coupling product formation through reaction with Grignard reagents, and cross-coupling reactions using Me L B r or H L Br in combination with Fe 0 (CO) 5 . Synthesis under light irradiation and moderate heating (50 °C) affords the aryl-Fe II complexes [Fe II (Br)( Me L )(CO)] ( 1 Me ) and [Fe II ( H L )(CO) 2 ]Br ( 1 H ). Exhaustive spectroscopic characterization of these rare low-spin diamagnetic species, including their crystal structures, allowed the investigation of their intrinsic reactivity.