Similar, Yet Different: Long-Range Metal–Metal Coupling and Electron-Transfer Processes in Metal-Free 5,10,15,20-Tetra(ruthenocenyl)porphyrin

Abstract

The electronic structure, redox properties, and long-range metal–metal coupling in metal-free 5,10,15,20-tetra­(ruthenocenyl)­porphyrin (H2TRcP) were probed by spectroscopic (NMR, UV–vis, magnetic circular dichroism (MCD), and atmospheric pressure chemical ionization (APCI)), electrochemical (cyclic voltammetry, CV, and differential pulse voltammetry, DPV), spectroelectrochemical, and chemical oxidation methods, as well as theoretical (density functional theory, DFT, and time-dependent DFT, TDDFT) approaches. It was demonstrated that the spectroscopic properties of H2TRcP are significantly different from those in H2TFcP (metal-free 5,10,15,20-tetra­(ferrocenyl)­porphyrin). Ruthenocenyl fragments in H2TRcP have higher oxidation potentials than the ferrocene groups in the H2TFcP complex. Similar to H2TFcP, we were able to access and spectroscopically characterize the one- and two-electron oxidized mixed-valence states in the H2TRcP system. DFT predicts that the porphyrin π-system stabilizes the [H2TRcP]+ mixed-valence cation and prevents its dimerization, which is characteristic for ruthenocenyl systems. However, formation of the mixed-valence [H2TRcP]2+ is significantly less reproducible than the formation of [H2TRcP]+. DFT and TDDFT calculations suggest the ruthenocenyl fragment dominance in the highest occupied molecular orbital (HOMO) energy region and the presence of the low-energy MLCT (Rc → porphyrin (π*)) transitions in the visible region with energies higher than the predominantly porphyrin-centered Q-bands.

Controlling Redox and Wirelike Charge-Delocalization Properties of Dinuclear Mixed-Valence Complexes with MCp*(dppe) (M = Fe, Ru) Termini Bridged by Metalloporphyrin Linkers

“…a nm-order highly delocalized system (>1 nm) (Figure d). Furthermore, modulation of the frontier orbital energies could be achieved by the choice of the metal centers embedded in the porphyrins. − In this study, we have found that the combination of the metal acetylide MV systems and the metalloporphyrins leads to highly delocalized and stable MV systems as well as wide variation of their redox and charge-delocalized behavior. This reflects that the Zn and Ni centers embedded in the porphyrin BL* can also act as efficient modulators for the properties of the dinuclear organometallic wire. − …”

A Neutral‐pH Aqueous Redox Flow Battery Based on Sustainable Organic Electrolytes

“…[43][44][45][46][47][48][49] Z. Zhao et al [50] used 1,1'bis(sulfonate)-ferrocene dianion disodium salt pared with the anthraquinone-2,7-disulfonic acid disodium salt; on the other hand, ferrocene decomposed under the acidic conditions used to stabilize the anthraquinone. [42] Considering our expertise in synthesis and applications of electro-active molecules, in particular metallocenes, [51][52][53][54] we synthesized in this work the 1,1'-bis(sulfonate)-ferrocene dianion disodium salt (DSÀ Fc) and two viologen-derivatives, as catholyte and anolyte, respectively, to produce a sustainable neutral-pH AORFB. The performances of the synthesized electrolytes were evaluated in terms of solubility, degradation capacity, retention, and electrical power generation.…”