Probing Electronic Effects in Tridentate Copper(I) Complexes by CIVP Spectroscopy

Area of Science:

• Coordination Chemistry
• Spectroscopy
• Catalysis

Background:

• Ligand electronic effects significantly impact catalytic activity.
• Accurate experimental quantification of ligand properties is vital for understanding and controlling chemical reactivity.
• Terpyridine ligands serve as valuable model systems for studying electronic effects.

Purpose of the Study:

• To experimentally quantify electronic effects in terpyridine ligands using copper complexes.
• To utilize cryogenic ion vibrational predissociation (CIVP) spectroscopy for this quantification.
• To employ nitrogen molecule (N2) tagged complexes as a probe system.

Main Methods:

• Cryogenic ion vibrational predissociation (CIVP) spectroscopy was performed on copper-terpyridine complexes tagged with N2.
• The N2 stretching vibration was used as a reporter chromophore to detect electronic perturbations.
• Quantum chemical calculations were employed to interpret the spectroscopic data and substituent effects.

Main Results:

• The N2 stretching vibrational frequency was sensitive to the electronic character of the terpyridine ligands.
• Substituent position and number on the terpyridine ligand influenced the N2 vibrational frequency.
• CIVP spectroscopy successfully probed both electronic and steric effects of the ligands.

Conclusions:

• The N2 bond acts as a sensitive reporter for electronic and steric properties of coordinating ligands.
• CIVP spectroscopy is a powerful technique for experimentally quantifying ligand electronic effects.
• Understanding these effects is crucial for designing and optimizing catalysts.