Photo-induced translocation of a Pdn moiety (n = 2, 7) on a conjugated polyene ligand.

Extended contiguous multiple π-coordination (CMπC) bonds play key roles at the molecular interface between extended π-conjugated sp2-carbon frameworks and metal clusters. However, their bond-rearrangement behavior including metal-translocation on an extended sp2-carbon framework has not been well understood. We found that a Pd2 moiety in a bis-tetraene sandwich complex shows metal-translocation either under thermal- or under photo-irradiation conditions, where the molar ratio of the isomers derived from metal-translocation is switchable through interconversion between the thermal equilibrium state and the photo-stationary state. Furthermore, an extended Pd7 chain sandwich complex having extended μ7-CMπC bonds undergoes metal-translocation on a carotene ligand under photo-irradiation conditions.