Mixed valency in ligand-bridged diruthenium frameworks: divergences and perspectives

Abstract

Emerging fundamental issues involving intramolecular electron transfer at the mixed valent diruthenium frameworks and its application prospects have been highlighted.

Ruthenium coordination preferences in imidazole‐containing systems revealed by electrospray ionization mass spectrometry and molecular modeling: Possible cues for the surprising stability of the Ru (III)/tris (hydroxymethyl)‐aminomethane/imidazole complexes

“…However, in order for this putative structure to match the measured mass, one of the three metal atoms would have to be in the reduced form (Ru II ), with the other two staying in the oxidized form (Ru III ). While the occurrence of the mixed‐valence ruthenium complexes had been well‐documented, including symmetrical structures where the metals have identical ligands, we are not aware of any reports of trinuclear mixed‐valence ruthenium complexes. Interestingly, the theoretical isotopic distribution of the [3Ru II,III,III + 6 T + 3O 2− ] 2+ ion does not provide an ideal fit to the experimentally measured distribution (see the orange bars in the Figure inset), and a better fit could be obtained should one assume that a minor fraction of the ions have all three ruthenium atoms in the +3 state (blue bars in Figure ) in addition to the mixed‐valence complex (red bars).…”

“…Energy calculation for different models of the Ru III Im 2 T 2 complex in aqueous solution (OPLS3 force field) Ru III ). While the occurrence of the mixed-valence ruthenium complexes had been well-documented, including symmetrical structures where the metals have identical ligands,32 we are not aware of any reports of trinuclear mixed-valence ruthenium complexes. Interestingly, the theoretical isotopic distribution of the [3Ru II,III,III + 6 T + 3O 2− ] 2+ ion does not provide an ideal fit to the experimentally measured distribution (see the orange bars in the…”

Modulation of Electrochemical and Spectroscopic Properties in Ru(II)‐Terpyridyl End‐Capped Homobimetallic Organometallic Complexes by Varying π‐Conjugated Organic Spacers

“…[19][20][21] The wire-like bimetallic congeners are of special interest for their fascinating electrochemical properties arising from their mixed-valence chemistry. [22][23][24][25][26][27][28][29] This class of rigid wirelike linear π-conjugated systems combined with two redoxactive metal termini, [ML x n -μ-(BL)-ML x n + 1 ] (BL = bridging ligand, M = redox active metal termini), generates mixed-valence state when one of the metal center undergoes a chemically or electrochemically reversible redox process generating different oxidation states in the two metal termini. Since the pioneering discovery of the binuclear Ru 2 (II,III) complex, [(NH 3 ) 5 Rupyrazine-Ru(NH 3 ) 5 ] 5 + by Creutz and Taube, [30][31] a significant number of mixed-valence metal complexes have been intensively investigated by varying the redox-active metallic termini and also modifying the π-conjugated bridges in order to tune the intermolecular electronic communication along the molecular backbone.…”

“…Over the past few years, mono‐ and bimetallic complexes having π‐conjugated bridging units have been the focus of extensive research interest because of their potential applications in molecular electronics, [1–8] electrochromism, [9–12] information storage, [13–14] ion sensing [15–18] and dye sensitized solar cells [19–21] . The wire‐like bimetallic congeners are of special interest for their fascinating electrochemical properties arising from their mixed‐valence chemistry [22–29] . This class of rigid wire‐like linear π‐conjugated systems combined with two redox‐active metal termini, [ML x n ‐μ‐(BL)‐ML x n+1 ] (BL=bridging ligand, M=redox active metal termini), generates mixed‐valence state when one of the metal center undergoes a chemically or electrochemically reversible redox process generating different oxidation states in the two metal termini.…”

Selective Formation of a Mixed‐Valence State from Linearly Bridged Oligo(aromatic diamines): Drastic Structural Change into a Folded Columnar Stack for Half‐filled Polycations

“…Mixed-valence (MV) states have unique magnetic or opto-electronic behaviors, [1] owingt ot he fact that they exhibitf acile electron transfer and/or charged elocalization. Dinuclear metal complexes are representative materials that adopt MV states, [2] which have two chemically equivalent sites with different redox states.I nc oordination polymersw ith multiple redox sites, even long-range interactions can be observed. [3] In contrast to the plethora of metal-based MV materials, less is known about pure organic MV molecules.…”