Towards a comprehensive model for the electronic and vibrational structure of the Creutz–Taube ion

Abstract

Since the synthesis of the Creutz-Taube ion, the nature of its charge localization has been of immense scientific interest, this molecule providing a model system for the understanding of the operation of biological photosynthetic and electron-transfer processes. However, recent work has shown that its nature remains an open question. Many systems of this type, including photosynthetic reaction centres, are of current research interest, and thereby the Creutz-Taube ion provides an important chemical paradigm: the key point of interest is the details of how such molecules behave. We lay the groundwork for the construction of a comprehensive model for its chemical and spectroscopic properties. Advances are described in some of the required areas including: simulation of electronic absorption spectra; quantitative depiction of the large interaction of the ion's electronic description with solvent motions; and the physics of Ru-NH 3 spectator-mode vibrations. We show that details of the solvent electron-phonon coupling are critical in the interpretation of the spectator-mode vibrations, as these strongly mix with solvent motions when 0.75!2J/l!1. In this regime, a double-well potential exists which does not support localized zero-point vibration, and many observed properties of the Creutz-Taube ion are shown to be consistent with the hypothesis that the ion has this character.

Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation

“…Bloch conduction may be regarded as a limit value for a disappearing barrier. In the latter case, we are talking about Hush-Reimers delocalization [27], where delocalization happens if λ < 2|H 12 |(U < 2|H 12 |).…”

“…The latter two states are also localized, but the final CI-state may be delocalized, if the final CI is strong. Hush-Reimers delocalization [27] means that a PES becomes flat between two total energy minima in the Marcus model. This leads to vibrational mode transfer [31].…”

Mixed‐Valence Ruthenium Complexes Rotating through a Conformational Robin–Day Continuum

“…Compound [3] 5+ has probably been investigated more extensively than any other MV complex, through detailed experimental measurements in the solid state [56][57][58] and in solution, [26,59,60] and also using quantum-chemical methods. [61][62][63][64][65][66] The UV-vis-NIR spectrum of [3] 5+ exhibits a single asymmetric band envelope with no notable shoulders (preventing simple Gaussian fitting). The asymmetric band shape can be explained by vibronic coupling, [1,13] which is not considered here.…”

Mixed valence: origins and developments

“…This was applied successfully to the mixed-valence M 2 SbCl 6 systems by Prassides & Day (1984). The importance of symmetric modes (neglected in the Piepho-Krausz-Schatz approach) has been stressed (Hush 1982;Reimers & Hush 2004;Reimers et al 2008); these modes becomes critical as J increases. In modelling the intervalence band envelopes of photosynthetic dimer cations, 50 symmetric and 20 asymmetric modes are involved (Reimers et al 2005).…”