Rutheniumethynyl-triarylamine mixed-valence conjugated system: syntheses, (spectro-)electrochemistry, and theoretical calculations

Abstract

We describe the synthesis and characterization of triarylamine ethynyl ruthenium conjugate (4-OMeC₆H₄)₂N-{C₆H₄-4-C≡C-RuCp* (dppe)}, 3. Its electronic and spectroscopy properties are investigated by anodic voltammetry, IR and UV–vis–NIR spectroelectrochemistry, and density functional theory (DFT) calculations. Results indicate that 3 undergoes two well-defined single-electron redox processes and that the Ru^II/III process occurs prior to the N^0/+ process as supported by IR spectra ν(C≡C) band changes from 3 to 3⁺ (Δν = 129 cm⁻¹) and spin-density distribution calculations of 3⁺. TDDFT calculations further reveal the NIR characteristic bands of singly oxidized 3⁺ from experimental spectroscopic absorptions, and we observe NAr₂→Ru charge transfer mixed with Ru-C≡C→phenyl bridge charge-transfer.

Keywords:

• Triarylamine
• ruthenium
• anodic voltammetry
• spectroelectrochemistry
• DFT calculations

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge the financial support from National Natural Science Foundation of China (21602049, 21472059, 21402057), the Natural Science Foundation of Hunan Province, China (No. 2017JJ3004), the Aid Programs for Technology Innovative Team and Key Discipline in Education Department of Hunan Province.