Synthesis, Structure, and Luminescence of Copper(I) Halide Complexes of Chiral Bis(phosphines)

For investigation of structure–property relationships in copper phosphine halide complexes, treatment of copper­(I) halides with chiral bis­(phosphines) gave dinuclear [Cu­((<i>R</i>,<i>R</i>)-<i>i</i>-Pr-DuPhos)­(μ-X)]₂ [X = I (<b>1</b>), Br (<b>2</b>), Cl (<b>3</b>)], [Cu­(μ-((<i>R</i>,<i>R</i>)-Me-FerroLANE)­(μ-I)]₂ (<b>5</b>), and [Cu­((<i>S</i>,<i>S</i>)-Et-FerroTANE)­(I)]₂ (<b>6</b>), pentanuclear cluster Cu₅I₅((<i>S</i>,<i>S</i>)-Et-FerroTANE)₃ (<b>7</b>), and the monomeric Josiphos complexes Cu­((<i>R</i>,<i>S</i>)-CyPF-<i>t</i>-Bu)­(I) (<b>8</b>) and Cu­((<i>R</i>,<i>S</i>)-PPF-<i>t</i>-Bu)­(I) (<b>9</b>); <b>1</b>–<b>3</b>, <b>5</b>, and <b>7</b>–<b>9</b> were structurally characterized by X-ray crystallography. Treatment of iodide <b>1</b> with AgF gave [Cu­((<i>R</i>,<i>R</i>)-<i>i</i>-Pr-DuPhos)­(μ-F)]₂ (<b>4</b>). DuPhos complexes <b>1</b>–<b>4</b> emitted yellow-green light upon UV irradiation at room temperature in the solid state. This process was studied by low-temperature emission spectroscopy and density functional theory (DFT) calculations, which assigned the luminescence to (M + X)­LCT (Cu₂X₂ to DuPhos aryl) excited states. Including Grimme’s dispersion corrections in the DFT calculations (B3LYP-D3) gave significantly shorter Cu–Cu distances than those obtained using B3LYP, with the nondispersion-corrected calculations better matching the crystallographic data; other intramolecular metrics are better reproduced using B3LYP-D3. A discussion of the factors leading to this unusual observation is presented