Fe-V sulfur clusters studied through photoelectron spectroscopy and density functional theory

Area of Science:

• * Materials Science and Physical Chemistry: Focuses on the electronic and structural properties of transition metal cluster anions.

Background:

• * Understanding the behavior of mixed-metal cluster anions is crucial for developing new materials and catalysts.
• * Previous studies have explored pure iron-sulfur clusters, but the influence of vanadium is less understood.

Purpose of the Study:

• * To investigate the structural isomers and electronic properties of iron-vanadium sulfur cluster anions (FeVS$_{1-3}$$^-$ and Fe$_m$V$_n$S$_{m+n}$$^-$).
• * To determine the factors controlling the first vertical detachment energies (VDEs) of these clusters.
• * To compare the properties of mixed Fe-V-S clusters with pure Fe-S clusters.

Main Methods:

• * Photoelectron Spectroscopy (PES) at 3.492 eV and 4.661 eV photon energies.
• * Density Functional Theory (DFT) calculations using the BPW91/TZVP level of theory.
• * Natural Bond Orbital (NBO) and Highest Occupied Molecular Orbital (HOMO) analyses.

Main Results:

• * Experimental VDEs for Fe-V sulfur clusters were reported and correlated with DFT calculations.
• * First VDEs of FeVS$_{1-3}$$^-$ increase with sulfur content, influenced by NBO/HOMO localization and partial charge.
• * Different structural isomers (e.g., tower vs. cubic) of Fe$_m$V$_n$S$_{m+n}$$^-$ exhibit distinct VDEs, explained by steric effects and electronic distributions.

Conclusions:

• * NBO/HOMO distributions and partial charge on localized sites are key to understanding VDE trends in Fe-V-S clusters.
• * Structural differences, particularly steric effects, significantly impact VDEs and properties of mixed Fe-V-S clusters.
• * The study provides insights into the fundamental properties of these mixed-metal clusters, aiding in comparisons with pure Fe-S systems.