Aurophilic Interactions in Three-Coordinate Gold(I) Complexes with C‑Clamp-like Structures

Area of Science:

• Inorganic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Aurophilic interactions in gold(I) complexes often lead to luminescence.
• Three-coordinate gold(I) complexes are less explored compared to two-coordinate counterparts.
• Bridging diphosphines are key ligands for constructing polynuclear gold complexes.

Purpose of the Study:

• To synthesize and characterize novel three-coordinate gold(I) complexes.
• To investigate the structural and photophysical properties of these complexes.
• To explore the role of bridging diphosphines in mediating aurophilic interactions.

Main Methods:

• One-pot synthesis involving bridging diphosphines (bis-(diphenylphosphino)-methane or 1,2-bis-(diphenylphosphino)-ethane) and gold(I) precursors.
• Crystallization to obtain single crystals of the target complexes.
• X-ray diffraction analysis to determine the molecular structure and gold-gold bond lengths.
• Photoluminescence spectroscopy at room temperature and low temperature (90 K).

Main Results:

• Synthesis of two novel gold(I) complexes: [(μ-dppm)-{Au-(bipy)}₂]-(PF₆)₂ and [(μ-dppe)-{Au-(bipy)}₂]-(BF₄)₂.
• The complexes feature c-clamp-like structures with significant aurophilic interactions (Au-Au distances of 3.0903(6) Å and 3.249(1) Å).
• Neither complex exhibited luminescence at room temperature or 90 K, contrary to expectations for similar gold(I) systems.

Conclusions:

• Bridging diphosphines can effectively stabilize three-coordinate gold(I) centers with aurophilic interactions.
• The observed c-clamp structure and non-luminescent nature highlight unique properties of these three-coordinate gold complexes.
• The lack of luminescence suggests that the specific coordination environment and bridging ligand influence photophysical behavior.