Rutheniumethynyl-triarylamine mixed-valence conjugated system: syntheses, (spectro-)electrochemistry, and theoretical calculations
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 RuII/III process occurs prior to the N0/+ 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.
