Metallo-oxides in nitrogen fixation

Abstract

Ammonia is released from the metallo-imide trans-[W(NH)(OMe)(Ph₂PCH₂CH₂PPh₂)₂]⁺ without degradation of the phosphine ligand assembly by a hydrolysis reaction which gives the oxide trans-[WOCl(Ph₂PCH₂CH₂PPh₂)₂]⁺; and this oxide and its Mo analogue are reduced at a mercury cathode in the presence of molecular nitrogen with phenol as a proton source to give trans-[M(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂](M = Mo or W); the primary reduction potentials of the Mo and W oxides are substantially positive of those of their isostructural imide counterparts and this suggests a possible role for oxides in biological nitrogen fixation.