Intervalence Electron Transfer in Pentaammineruthenium Complexes of Dipyridylpolyenes, Dipyridylthiophene, and Dipyridylfuran

Abstract

Intervalence transitions have been observed between pentaammineruthenium(II) and -ruthenium(III) groups linked by dipyridylpolyenes, dipyridylthiophene, and dipyridylfuran. For all compounds, the comproportionation constants have been determined, to obtain corrected spectra of the mixed-valence forms, and the intervalence band profiles have been obtained by spectral deconvolution. The longest dipyridylpolyenes (with 3 and 4 double bonds) give only ill-defined bands, which does not allow us to reach definitive conclusions on the decay law of the electronic interaction with distance. On the contrary, dipyridylthiophene and -furan present a better resolution of the intervalence transition, which is ascribed to a better coplanarity and rigidity.

Organic Mixed Valence Systems. II. Two-Centers and Three-Centers Compounds with Meta Connections around a Central Phenylene Ring

“…4 The method employed to get the effective electronic coupling between the redox sites for 1 is the same as the one used for bimetallic mixed-valence ruthenium compounds. 5 The comproportionation equilibrium between the mixed valence and the homovalent species is described by one thermodynamic constant (K c ). After correction from the comproportionation constant and detailed analysis of the intervalence band (cf Figure 4), one gets the parameter V ab ) 181 cm -1 (cf Table 1).…”

Mixed Valence Creutz−Taube Ion Analogues Incorporating Thiacrowns: Synthesis, Structure, Physical Properties, and Computational Studies

“…33 Turning back to the pyrazine bridged complexes, it is notable that although 1-3 all possess thiacrown ligands with the same S 4 donor set, their IVCT bands differ slightly in energy and shape. We have observed similar effects on related systems involving bridging ligands with two bidentate sites; but in these cases the differences, particularly in electrochemical properties, were larger.…”

Magnetic perturbation of the redox potentials of localized and delocalized mixed-valence complexes

“…For example, recent some works has shown significant communication without a resolved separation between the redox processes [35,32]. In such cases, whenever possible, K c has to be determined by other means, such as spectrometric titration [36,37]. In the case of a single twoelectron wave, as observed for 12 (see below), the two standard potentials can also be derived from the location of the midpoint between the anodic and cathodic peaks and the distance between them (DE p ), provided the kinetics of the electron-transfer processes do not affect the cyclic voltammetric response [32] f½M red -B-½M red g nþ þ f½M ox -B-½M ox g ðnþ2Þþ…”