Integrated Experimental and Computational K-Edge X-ray Absorption Near-Edge Structure Analysis of Vanadium Catalysts

X-ray absorption near-edge structure (XANES) spectroscopy is a powerful tool to reveal key structural and electronic features of isolated catalytic sites, yet insights into the molecular more detailed orbital analysis through combination experimental computed XANES are necessary for accurate interpretation spectra, especially when significant heterogeneity exists among sites. Herein, we present an integrated computational strategy determine both primary secondary bonding interactions within pre-edge region organovanadium complexes, which was developed using series well-defined vanadium complexes then applied characterization supported olefin hydrogenation catalyst. Time-dependent density functional theory used predict energy with variety oxidation states local coordination environments. A calibration scheme incorporating different functionals basis sets established, resulting in optimized that accurately predicts energies mean absolute error 0.40 eV. Second-shell (e.g., V···V) effects identified dominant contributions multi-vanadium complexes. Orbital also provided confirmation vanadium-hydride formation combined active species caused shift broadening peak after hydrogen treatment silica-supported pre-catalyst. This work further elucidates simulations techniques potentially guiding surface organometallic chemistry.