Tungsten-alkylidyne (–carbyne) complexes, possess a vast and synthetically accessible framework with oxidation potentials tunable over 2 V and are thus good candidates for achieving the photochemical one-electron reduction of CO<sub>2</sub>, which could allow for a wide range of synthetic products not achievable by lower free energy reduction pathways. Therefore, we study their one-electron transfer properties to establish the relevant design principles. The regulation of redox properties of an extensive set of tungsten-alkylidyne complexes is analyzed by combining ligand design and synthesis, electrochemistry and computational modeling based on free energy calculations of oxidation potentials at the density functional theory level. The observed linear correlation between oxidation potentials and HOMO energies is found to be consistent with the approximately constant solvation free energy difference between reduced and oxidized species over the complete set. The coordination bond length of axial ligands is found to be an indicator of the positioning of the frontier orbitals that regulate the redox properties of the complexes.

Regulation of the redox properties of tungsten-alkylidyne complexes by ligand design

253rd National Meeting (2017)

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