Electron-transfer reactions in nitrogen fixation. Part 2. The electrosynthesis of ammonia: identification and estimation of products

Abstract

Protonation of trans-[W(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂] with toluene-p-sulphonic acid gives the hydrazido cation trans-[W(NNH₂)(p-MeC₆H₄SO₃)(Ph₂PCH₂CH₂PPh₂)₂]⁺. Reduction of this cation at a Hg-pool electrode in a tetrahydrofuran electrolyte under N₂(1 atm) affords free ammonia with regeneration of the parent dinitrogen complex in excellent yield. Protonation of the regenerated product allows the system to be cycled and this can be performed in one vessel, the cathode compartment of the electrolysis cell.