Revisiting the Robin-Day Classification through Switchable Electronic States in Multimetallic Vanadium Oxides

Area of Science:

• Inorganic Chemistry
• Materials Science
• Computational Chemistry

Background:

• Polyoxovanadate-alkoxide clusters are redox-active and electronically tunable.
• The oxygen-deficient [(V6O5)(μ6-O)(μ2-OCH3)12] cluster serves as a model for studying redox state localization and delocalization.

Purpose of the Study:

• To introduce and investigate redox topology modulation as a mechanism controlling electromer stability in polyoxovanadate clusters.
• To explore the impact of ligand coordination and electronic structure on redox behavior and molecular switching capabilities.

Main Methods:

• Computational studies, including density functional theory (DFT) and time-dependent DFT (TD-DFT), were employed.
• Analysis of redox topology, ligand-field tuning, and photoinduced intervalence charge transfer was performed.

Main Results:

• The noncoordinated cluster exhibits a localized, hybrid Robin-Day class I/II ground state with a V(III) center.
• Ligand coordination of strong donors destabilizes the localized topology, favoring an all-V(IV) electromer ground state.
• Photoexcitation of V(IV) species induces charge transfer, leading to a valence-trapped class II excited state.

Conclusions:

• Redox topology modulation is a viable design principle for creating molecular switches tunable by chemical stimuli or light.
• The Robin-Day classification may require revision for multicenter systems, with valence behavior being excitation-specific.