A new heteroleptic phosphorescent cuprous complex supported by a BINAP ligand: synthesis, structure, luminescence...

Luminescent cuprous complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The heteroleptic cuprous complex solvate rac-(acetonitrile-κN)(3-aminopyridine-κN)[2,2'-bis(diphenylphosphanyl)-1,1'-binaphthyl-κ²P,P']copper(I) hexafluoridophosphate dichloromethane monosolvate, [Cu(C₅H₆N₂)(C₂H₃N)(C₄₄H₃₂P₂)]PF₆·CH₂Cl₂, conventionally abbreviated as [Cu(3-PyNH₂)(CH₃CN)(BINAP)]PF₆·CH₂Cl₂, (I), where BINAP and 3-PyNH₂ represent 2,2'-bis(diphenylphosphanyl)-1,1'-binaphthyl and 3-aminopyridine, respectively, is described. In this complex solvate, the asymmetric unit consists of a cocrystallized dichloromethane molecule, a hexafluoridophosphate anion and a complete racemic heteroleptic cuprous complex cation in which the cuprous centre, in a tetrahedral CuP₂N₂ coordination, is coordinated by two P atoms from the BINAP ligand, one N atom from the 3-PyNH₂ ligand and another N atom from a coordinated acetonitrile molecule. The UV-Vis absorption and photoluminescence properties of this heteroleptic cuprous complex have been studied on polycrystalline powder samples, which had been verified by powder X-ray diffraction before recording the spectra. Time-dependent density functional theory (TD-DFT) calculations and a wavefunction analysis reveal that the orange-yellow phosphorescence emission should originate from intra-ligand (BINAP) charge transfer mixed with a little of the metal-to-ligand charge transfer ³(IL+ML)CT excited state.