Syntheses and luminescence behavior of tetranuclear copper(I) diynyl complexes: X-ray crystal structure of [Cu4(PPh3)4(μ3-η1-CCCCPh)4]

A series of luminescent tetranuclear cuboidal copper(I) diynyl complexes, [Cu4(PAr3)4(μ3-η1-CCCCR′)4] (Ar=Ph, R′=Ph, C6H4CH3-p, C6H4OCH3-p; Ar=C6H4CH3-p, C6H4F-p, R′=Ph) has been synthesized and characterized. The X-ray crystal structure of [Cu4(PPh3)4(μ3-η1-CCCCPh)4] has been determined. The origin of the low-energy emission in the complexes is assigned as derived from a metal-centered 3d94s1 state, mixed with LMCT [diynyl→Cu4] and IL [π–π*(diynyl)] states.