Excited state properties of a copper(I) benzene complex. Emission from a metal-to-ligand charge transfer state

The solid compound Cu2(CF3SO3)2(C6H6) shows an intense emission at λmax=518 nm (φ∼10−2, τ=0.5 μs) which is suggested to originate from a CuI to benzene metal-to-ligand charge transfer (MLCT) triplet. The spin-allowed MLCT transition gives rise to an excitation maximum at λ=318 nm which appears also as long-wavelength band at λmax=315 nm in the absorption spectrum of the complex in solution.