Helicity induction by innocent anion in a quadruple stranded cage

Anion induced twisted disposition of four units of a bidentate ligand around two palladium(II) centers in the cage of [Pd2L4](ClO4)4 formulation resulted in a helical structure. The crystal structure reveals the existence of both M and P enantiomers. The disposition of one of the arms is noticeably different from the other three, hence the molecular symmetry of the helicate is lowered. The encapsulation of perchlorate anion within the cage pocket with H-bonding interactions provided the driving force for the helicity. However, the analogues complex [Pd2L4](NO3)4 with nitrate as counter anion is nonhelical. Formation of helical and nonhelical Pd2L4 arrangement by mere change of counter anion was not reported hence it is a new finding.