Light Activated Release of Nitrile Ligands from trans-Ru(L)(PPh₃)₂(nitrile) Complexes

Area of Science:

• Coordination Chemistry
• Organometallic Chemistry
• Photochemistry

Background:

• Ruthenium complexes are versatile in catalysis and photochemistry.
• Ligand design is crucial for tuning complex properties.
• Nitrile ligands offer unique electronic and steric properties.

Purpose of the Study:

• To synthesize and characterize novel trans-ruthenium(II) complexes with dipyridine-based ligands (L) and nitrile ligands.
• To investigate the electrochemical and photochemical behavior of these complexes.
• To explore the relationship between ligand structure and ligand release dynamics.

Main Methods:

• Synthesis of trans-RuL(PPh3)2(nitrile) and {RuL(PPh3)2}2-μ-(nitrile) complexes.
• Characterization using spectroscopic and analytical techniques.
• Electrochemical and photochemical measurements to study behavior and ligand dissociation.

Main Results:

• Successful synthesis and characterization of various ruthenium complexes with dpp, bpi, or Pbpy ligands and different nitrile ligands.
• Investigation revealed that complexes with significant nitrile contribution to 3MLLCT exhibit nitrile ligand release.
• Dissociation constants up to 8.09 × 10-4 s-1 were observed for specific ligand combinations (L=dpp or Pbpy; nitrile=4-dibenzontirile or 4-ethynylbenzonitrile).

Conclusions:

• The study demonstrates the tunability of ruthenium complex properties through ligand selection.
• Nitrile ligand lability is influenced by the electronic properties of the ancillary ligands and the nature of the nitrile.
• These findings contribute to the understanding of ligand dissociation mechanisms in ruthenium complexes, with potential implications for their use in functional materials or catalytic systems.