Thermodynamic and Structural Factors That In fl uence the Redox 2 Potentials of Tungsten − Alkylidyne Complexes

8 ABSTRACT: The thermodynamic and structural factors that influence the redox properties of 9 an extensive set of tungsten−alkylidyne complexes W(CR)L4X are analyzed by combining 10 synthesis, electrochemistry, and computational modeling based on free energy calculations of 11 oxidation potentials at the density functional theory level. The observed linear correlations 12 among oxidation potentials, HOMO energies, and gas-phase ionization energies are found to 13 be consistent with the approximately constant solvation free energy differences between 14 reduced and oxidized species over the complete set. The W−X bond length, trans to the 15 alkylidyne ligand, is found to be a good descriptor of the positioning of the key frontier orbitals that regulate the redox properties 16 of the complexes. 17