From Hetero- to Homochiral Bis(metallahelicene)s Based on a PtIII−PtIII Bonded Scaffold: Isomerization, Structure, and Chiroptical Properties

Hetero- and homochiral diastereomeric bis(metallahelicene)s have been synthesized. They possess a rare PtIII−PtIII scaffold bridged by benzoato ligands. It is shown that heterochiral (P,M)-bis(PtIII-[6]helicene) can isomerize into the homochiral (P,P)- and (M,M)-bis(PtIII-[6]helicene). A theoretical study shows a unique σ−π conjugation between the two π-helices and the σ-PtIII−PtIII scaffold that impacts the strong chiroptical properties.