A Novel Luminescent μ4-Selenido-Bridged Copper (I) Tetramer

Abstract

A novel soluble tetranuclear copper (I) cluster containing an unsubstituted μ4-selenido moiety, [Cu4(μ-dppm)4-(μ4-Se)]2+ (1), has been synthesized and characterized by X-ray crystallography. Its photophysical and electrochemical properties have been studied. It is envisaged that the emissions of 1 are associated with a ligand-to-metal charge-transfer LMCT [(Se2-) → Cu4] triplet excited state, and probably with mixing of a metal-centered (3d94s1) Cu (I) state. The phosphorescent state of 1 undergoes facile electron-transfer quenching with a series of pyridinium acceptors. An excited-state reduction potential, E°[Cu4(μ-dppm)4(μ4-Se) 3+/2+*], of -1.55(10) V vs SSCE has been estimated. Crystal data: monoclinic, space group C2/c (No. 15), a = 27.913(9) Å, b = 16.512-(9) Å, c = 24.10(1) Å, β = 109.29(2)°, V = 10483(5) Å3, Z = 4.