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 Pt-III-Pt-III scaffold bridged by benzoato ligands. It is shown that heterochiral (P,M)-bis(Pt-III-[6]helicene) can isomerize into the homochiral (P,P)- and (M,M)-bis-(Pt-III-[6]helicene). A theoretical study shows a unique sigma-pi conjugation between the two pi-helices and the sigma-Pt-III-Pt-III scaffold that impacts the strong chiroptical properties.