Luminescent monomeric and polymeric cuprous halide complexes with 1,2-bis(3,5-dimethylpyrazol-1-ylmethyl)-benzene as ligand

Abstract Reaction of cuprous bromide with equimolar amounts of 1,2-bis(3,5-dimethylpyrazol-1-ylmethyl)-benzene (dpb) affords a mononuclear three-coordinated complex [CuBr(dpb)] (F2) with dpb acting as a chelating ligand. In contrast, using cuprous iodide instead under the same conditions gives the polymeric compound [Cu₂I₂(dpb)]_n (F1) which contains double-bridging iodine atoms. The complexes were characterized by element analysis and ¹H NMR spectroscopy, and the crystal structures were determined by single-crystal X-ray diffraction methods. The Cu(I) complexes are luminescent in the solid state at ambient temperature. Intense orange emission for complex F1 is observed, with maxima at 593 nm, probably ascribed to a combination of a halide-to-metal charge transfer and copper-centered d → s, p transitions. F2 exhibits a blue photoluminescence, with emission maximum at 515 nm, assigned to metal-to-ligand charge-transfer excited states, probably mixed with some halide-to-ligand characters.