Phosphorescent fac-Bis(triarylisocyanide) W(0) and Mo(0) Complexes

Area of Science:

• Organometallic Chemistry
• Photochemistry
• Materials Science

Background:

• Tungsten (W) and Molybdenum (Mo) complexes are of interest due to their diverse electronic and photophysical properties.
• Isocyanide ligands offer unique coordination modes and electronic tunability in metal complexes.
• Developing novel luminescent materials with strong photoreduction capabilities is crucial for various applications.

Purpose of the Study:

• To synthesize and characterize novel homoleptic W(0) and Mo(0) complexes featuring bis(triarylisocyanide) ligands with bulky substituents.
• To investigate the structural, spectroscopic, photophysical, and electrochemical properties of these newly synthesized complexes.
• To evaluate their potential as strong photoreductants.

Main Methods:

• Synthesis of homoleptic W(0) and Mo(0) complexes with bis(triarylisocyanide) ligands.
• Spectroscopic characterization (e.g., NMR, UV-Vis, emission spectroscopy).
• X-ray crystallography for structural determination.
• Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) calculations.
• Electrochemical measurements (cyclic voltammetry) to determine redox potentials.

Main Results:

• Hourglass-shaped complexes with facial coordination of tridentate ligands were structurally confirmed.
• The complexes exhibit luminescence in both fluid solutions and solid states, with distinct emission maxima, lifetimes, and quantum yields for W(0) and Mo(0) complexes.
• DFT/TDDFT calculations suggest metal-to-ligand charge transfer (MLCT) transitions are responsible for low-energy absorption bands.
• Reversible M+/0 redox couples were observed, and excited-state reduction potentials indicate strong photoreductant capabilities.

Conclusions:

• Novel W(0) and Mo(0) complexes with bulky bis(triarylisocyanide) ligands have been successfully synthesized and characterized.
• The complexes display interesting photoluminescent properties and possess potentials as strong photoreductants due to their favorable excited-state reduction potentials.
• The structural and electronic properties suggest potential applications in areas requiring efficient electron transfer processes.