A novel paradigm for metal-induced ring flipping in the copper(II) complex of 1,2-bis(N-methylbenzimidazol-2′-yl)benzene triflate

The crystal structures of 1,2-bis(N-methylbenzimidazol-2′-yl)benzene (bmbz) 1 and its copper(II) triflate complex 2 have revealed a CuII-induced conformational change in which one of the N-methylbenzimidazole moieties is entirely flipped, as compared to the free ligand, which mimics histidine side-chain flipping in the copper complex of RNase A, and leads to a twisted V-shaped conformation of the ligand in metal complex.