Synchronized motion and electron transfer of a redox-active rotor.

We have constructed a series of copper complexes with asymmetric 4,6-substituted 2-pyrimidyl coordination units, which form two coordination isomers via rotation of the pyrimidine ring. Redox-active ferrocenyl moieties were introduced at the 4-positions of the pyrimidine as rotating units in these complexes. The stability and dynamics of the rotative interconversion could be tuned using the structure of the rotor to accommodate a large ferrocene unit within the inner space of the complex. Among these compounds, a complex with a ferrocenylvinyl substituent showed synchronized intramolecular electron transfer between the copper and the ferrocenyl moiety with rotational motion. That is, the oxidation state of the ferrocenyl unit depended on its position within a cyclic trajectory.