Synthesis, structure, photophysics, time-resolved emission spectroscopy and electrochemistry of luminescent copper(I) acetylide complexes

Abstract

A series of soluble trinuclear copper(I) complexes containing mono- and bi-capped µ₃-η¹-acetylides [Cu₃(dppm)₃(µ₃-η¹-CCR)]²⁺ and [Cu₃(dppm)₃(µ₃-η¹-CCR)₂]⁺(dppm = Ph₂PCH₂PPh₂, R = Ph or Bu^t) have been synthesized and shown to exhibit long-lived dual luminescent behaviour. Their photophysics and electrochemistry and those of a mixed halide–acetylide capped trinuclear copper(I) complex [Cu₃(dppm)₃(µ₃-η¹-CCBu^t)(µ₃-Cl)]⁺ have been investigated. The origin of the low-energy emission (λ_em 525–700 nm) is ascribed to states of ds/l.m.c.t. admixture with large l.m.c.t. (ligand to metal charge transfer) character. The crystal structure of [Cu₃(dppm)₃(µ₃-η¹-CCBu ^t)][PF₆]₂ has been determined. The complex consists of an isosceles triangular array of copper atoms with Cu–Cu distances of 2.910(1), 2.941(2) and 3.175(1)Å.