PREPARATION AND PROPERTIES OF DIAZENIDO,HYDRAZIDO(2-), AND HYDRIDO-HYDRAZIDO(2-) COMPLEXES OF TUNGSTEN. X-RAY PHOTOELECTRON SPECTROSCOPY OF DINITROGEN AND HYDRAZIDO(2-) COMPLEXES OF MOLYBDENUM AND TUNGSTEN

Abstract

Reactions of HBr with trans-W(N₂)₂(dppe)PPh₂Me)₂] (1) (dppe = Ph₂CH₂CH₂PPh₂) result in protonation of coordinated N₂ but no formation of ammonia or hydrazine. The tungsten-containing product depends upon the reaction conditions: (i) in MeOH, the product formed is WBr(NNH₂) (dppe)(PPh₂Me)₂]HBr₂ (2) which converts to the hydride, WBr₂(H)(NNH₂(dppe)(PPh₂Me)](Br(3), with loss of phosphine in THF or CH₂Cl₂, (ii) in THF or CH₂Cl₂, the hydride (3) is formed directly. Reaction of 2 with Na₂CO₃ in MeOH results in the loss of HBr and the formation of the diazenido complex WBr(NNH)(dppe)(PPh₂Me)₂] which reacts further with Na₂CO₃ in benzene under N₂ to lose HBr and form a mixture of 1 and trans-W(N₂)(dppe)₂]. The reaction of 1 with aqueous HF forms WF(NNH₂)(dppe)(PPh₂Me)₂]BF₄. The X-ray photoelectron spectra of trans-M(N₂)₂ (dppe)₂], MBr(NNH₂)(dppe)₂Br (M = Mo, W), WCl(NNH₂)(dppe)₂]Cl, WCl(N)(dppe)₂]Cl and WCl(NH) (dppe)₂] are reported. In all of these complexes, nitrogen is in a highly reduced form.