Comparison of Thermodynamic Energies for Elementary Steps of Anionic Hydrides to Release Hydride Ions in Acetonitrile

Abstract

AbstractIn this work, six thermodynamic parameters of 10 anionic hydrides XH− ascorbic acid (iAscH−), alcohol anions, imine anion, activated olefin anions and diene anions and their intermediates in hydride transfer process were researched. The hydride‐donating, hydrogen‐atom‐donating and election‐donating abilities of XH−, and the electron‐accepting abilities of X were also discussed. Two physical parameters of free radical XH⋅, homolytic Gibbs free energy to release hydrogen atom ΔGoHD(XH⋅), heterolytic Gibbs free energy to release proton ΔGoPD(XH⋅), were determined to evaluate the antioxidant ability and acidity of intermediate XH⋅ in thermodynamics. The structure‐activity relationship of XH−, XH⋅ and X were carefully discussed. It's easy to find that the hydride‐donating abilities of XH− are stronger than their neutral compounds XH2; except for iAscH−; the hydride‐donating abilities of XH− are stronger than their hydrogen‐atom‐donating abilities; the hydrogen‐atom‐donating abilities of XH− are weaker than their intermediate radicals XH⋅; the unsaturated compounds X are easier to accept electrons than the anionic hydrides XH− to donate electrons. This paper plays an important role in determining the mechanism of anionic hydride to release hydride ion and provides a new idea for the design and synthesis of more active hydride, hydrogen and electron donors.