Preparation, reactivity and photoluminescence of copper(I) borohydride complexes with bis[(2-diphenylphosphino)phenyl] ether as chelating ligand

Bis[(2-diphenylphosphino)phenyl] ether (DPEphos) was used as chelating ligand to prepare the corresponding borohydride complex [Cu(κ2–BH4)(DPEphos)], whose structure was ascertained spectroscopically and by means of X-ray diffraction. The spectroscopic assignments related to the coordinated borohydride were confirmed by preparing the isotopologue [Cu(κ2–BD4)(DPEphos)]. Reaction of [Cu(κ2–BH4)(DPEphos)] with triflic acid afforded the dimer [Cu2(μ–BH4)(DPEphos)2][OTf] (OTf = triflate). The borohydride complexes exhibited appreciable blue emission upon excitation with UV light at room temperature. [Cu(κ2–BH4)(DPEphos)] revealed to be a suitable precursor for the preparation of luminescent heteroleptic copper(I) complexes having general formula [Cu(N^N)(DPEphos)]+ (N^N = 1,10-phenantroline, 2,9-dimethyl-1,10-phenantroline, 2,2’-bypiridine, 4,4’-dimethyl-2,2’bipyridine).