Utilization of a Nonemissive Triphosphine Ligand to Construct a Luminescent Gold(I)-Box That Undergoes Mechanochromic Collapse into a Helical Complex.

Luminescent gold(I) complexes ([Au(Triphos)Cl](PF)·2(CHCH), [Au(Triphos)Cl](AsF)·8(CHCH), and [Au(Triphos)Cl](SbF)·7(CHCH) where Triphos = bis(2-diphenylphosphinoethyl)phenylphosphine) with a boxlike architecture have been prepared and crystallographically characterized. A chloride ion resides at the center of the box with two of the six gold(I) ions nearby. Mechanical grinding of blue luminescent crystals containing the cation, [Au(Triphos)Cl], results in their conversion into amorphous solids with green emission that contain the bridged helicate cation, [μ-Cl{Au(Triphos)}]. A mechanism of the mechanochromic transformation is proposed. The structures of the blue-emitting helicate, [Au(Triphos)](CFSO)·4(CHCH)·HO, and the green-emitting bridged-helicate, [μ-Cl{Au(Triphos)}](PF)·3CHOH have been determined by single crystal X-ray diffraction.