Cationic silyldiazenido complexes of the Fe(diphosphine) 2 (N 2 ) platform: structural and electronic models for an elusive first intermediate in N 2 fixation.

The first cationic Fe silyldiazenido complexes, [Fe(PP)2 (NN-SiMe3 )]+ [BArF 4 ]- (PP = dmpe/depe), have been synthesised and thoroughly characterised. Computational studies show the compounds to be useful structural and electronic surrogates for the more elusive [Fe(PP)2 (NN-H)]+ , which are postulated intermediates in the H+ /e- mediated fixation of N2 by Fe(PP)2 (N2 ) species.