BIBLIOS

Document type
Journal articles

Document subtype
Full paper

Title
A lacunary tungstomolybdophosphate as an electronic pendulum: The “blue” electron under examination

Participants in the publication
Nuno A. G. Bandeira (Author)
BioISI - Biosystems & Integrative Sciences Institute
Dep. Química e Bioquímica
BioISI
Huizhang Liu (Author)
Maria José Calhorda (Author)
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA

Summary
The photoreduction of a Keggin type lacunary tungstomolybdophosphate, α-(Bu4N)4[H3PW9Mo2O39], in acetonitrile, led to the formation of a monoreduced lacunary heteropoly anion, or a one electron reduced “heteropoly blue” species, whereby the added “blue” electron was captured by the molybdenum atoms. The magnetic properties and behavior of the “blue” electron were studied by a modified Evans nuclear magnetic resonance method (small downshift of the 31P signal) and variable-temperature electron paramagnetic resonance (g = 1.936 for MoV). The intermolecular exchange of the “blue” electron was limited by a geometrical factor, which requires the contact between Mo caps to exchange it between the heteropoly couple. The intramolecular exchange of the “blue” electron between Mo atoms was rather fast (5.3 × 109 s−1), with a rate of more than six orders of magnitude larger than the intermolecular exchange rate. Density functional theory was used to determine the most prevalent protonation sites in the mixed lacunary isomers with the aim of studying the intramolecular electron transfer pathway in the isolated [H4PW9Mo2O39]4− species. The singly occupied molecular orbital (SOMO) is essentially localized in one of the two nonequivalent molybdenum sites. The kinetics of the intramolecular electron exchange equilibrium MoV + MoVI → MoVI + MoV between the two molybdenum atoms bridged by an oxygen atom was found to be fast in agreement with the experimental result. The transition state is of mixed-valence type, with the SOMO delocalized over the Mo—O—Mo group. Spectroscopic parameters were found to be in fair agreement with experimental results.


Where published
The Journal of Chemical Physics

Publication Identifiers
ISSN - 0021-9606

Publisher
AIP Publishing



Document Identifiers
DOI - https://doi.org/10.1063/5.0039092
URL - http://dx.doi.org/10.1063/5.0039092

Rankings
SCIMAGO Q1 (2020) - 1.071 - Physical and Theoretical Chemistry
Web Of Science Q1 (2020) - 3.488 - PHYSICS, ATOMIC, MOLECULAR & CHEMICAL - SCIE

Tags
Isomerism Metal oxides Chemical bonding Nuclear magnetic resonance spectroscopy Photochemistry Transition state Potential energy surfaces Paramagnetism Density functional theory Electron transfer