Lewis Base-Enhanced C–H Bond Functionalization Mediated by a Diiron Imido Complex

High Resolution Image Download MS PowerPoint Slide Herein, we investigate the effects of ligand design on the nuclearity and reactivity of metal–ligand multiply bonded (MLMB) complexes to access an exclusively bimetallic reaction pathway for C–H bond functionalization. To this end, the diiron alkoxide [Fe 2 ( Ph Dbf) 2 ] ( 1 ) was treated with 3,5-bis(trifluoromethyl)phenyl azide to access the diiron imido complex [Fe 2 ( Ph Dbf) 2 (μ-NC 8 H 3 F 6 )] ( 2a ) that promotes hydrogen atom abstraction (HAA) from a variety of C–H and O–H bond containing substrates. A diiron bis(amide) complex [Fe 2 ( Ph Dbf) 2 (μ-NHC 8 H 3 F 6 )(NHC 8 H 3 F 6 )] ( 3 ) was generated, prompting the isolation of the analogous bridging amide terminal alkoxide [Fe 2 ( Ph Dbf) 2 (μ-NHC 8 H 3 F 6 )(OC 19 H 15 )] ( 4 ) and the asymmetric pyridine-bound diiron imido [Fe 2 ( Ph Dbf) 2 (μ-NC 8 H 3 F 6 )(NC 5 H 5 )] ( 6a ). We found that 6a is competent for toluene amination, indicating the effect of Lewis base-enhanced C–H bond functionalization. Mechanistic investigations suggest that the bimetallic bridging imido complex is the reactive intermediate as no monometallic species is detected during the time course of the reaction.