Novel Luminescent Tetranuclear and Pentanuclear Copper(I)−Dithiolates

Tetranuclear [Cu₄(μ₂-dppm)₃(μ₂-μ₂-NS₂)(μ₂-μ₄-NS₂)] (1) and pentanuclear [Cu₅(μ₂-dppm)₄(μ₃-μ-₃-NS₂)₂]PF₆ (2·PF₆) (dppm = bis(diphenylphoshino)methane, NS₂^2- = 1,8-naphthalenedithiolate) were synthesized from the reactions between NS₂^2- and [Cu₂(μ₂-dppm)₂(CH₃CN)₂](PF₆)₂. Compound 1 features a square Cu₄ core capped by a 5-coordinate S atom while 2·PF₆ exhibits an unprecedented square planar Cu₅ core. Both complexes display dual emissions at 480 and 620 nm which arise from ligand-centered nπ* and ligand−metal charge-transfer excited states, respectively.