Enantiopure Cyclometalated Rh(III) and Ir(III) Complexes Displaying Rigid Configuration at Metal Center: Design, Structures, Chiroptical Properties and Role of the Iodide Ligand

Enantiopure N-heterocyclic carbene half-sandwich metal complexes of the general formula [Cp*M(C^C:)I] (M = Rh, Ir; C^C: NI-NHC; NI-H Naphthalimide; NHC carbene) are reported. The rhodium compound was obtained as a single isomer displaying six membered metallacycle and resolved on chiral column chromatography to corresponding enantiomers (S)-[Cp*Rh(C^C:)I] (S)-2 (R)-[Cp*Rh(C^C:)I] (R)-2. iridium congener, however, furnishes pair regioisomers, which were into (S)-[Cp*Ir(C^C:)I] (S)-3 (R)-[Cp*Ir(C^C:)I] (R)-3 (S)-4 (R)-4. These regioisomers differ from each other, only by size metallacycle; five-membered for 3 six-membered 4. molecular structures Moreover, chiroptical properties these compounds presented discussed. display exceptional stable configurations at center in solution with enantiomerization barrier ΔG≠ up 124 kJ/mol. This is because nature naphthalimide-NHC clamp ligand iodide contribute their configuration’s robustness. In contrast related reported literature, often labile solution.