Optically probing the localized to delocalized transition in Mo₂–Mo₂ mixed-valence systems

A transition of mixed-valence systems from Class II to Class III crossing the Class II–III borderline is achieved by four thienylene-bridged Mo2 dimers, and is probed using spectral parameters of intervalence charge transfer absorption (band energy, intensity and shape). This study offers fresh and detailed observations of optical behaviors of MV compounds in different regimes.