Divergent CO 2 Activation by Tuning the Lewis Acid in Iron-Based Bimetallic Systems.

Bimetallic motifs mediate the selective activation and functionalization of CO 2 in metalloenzymes and some recent synthetic systems. In this work, we build on the nascent concept of bimetallic frustrated Lewis pairs (FLPs) to investigate the activation and reduction of CO 2 . Using the Fe 0 fragment [(depe) 2 Fe] (depe=1,2-bis(diethylphosphino)ethane) as base, we modify the nature of the partner Lewis acid to accomplish a divergent and highly chemoselective reactivity towards CO 2 . [Au(PMe 2 Ar)] + irreversibly dissociates CO 2 , Zn(C 6 F 5 ) 2 and B(C 6 F 5 ) 3 yield different CO 2 adducts stabilized by push-pull interactions, while Al(C 6 F 5 ) 3 leads to a rare heterobimetallic C-O bond cleavage, and thus to contrasting reduced products after exposure to dihydrogen. Computational investigations provide a rationale for the divergent reactivity, while Energy Decomposition Analysis-Natural Orbital for Chemical Valence (EDA-NOCV) method substantiates the heterobimetallic bonding situation.