Recent developments in synthetic nitrogen fixation
Within the background of biological nitrogen fixation mediated by the enzyme nitrogenase, transition-metal complexes capable of binding and activating dinitrogen towards protonation and reduction have been synthesised. Of particular interest in this research area has been the transition-metal mediated conversion of dinitrogen to ammonia (stoichiometric and catalytic) and the elucidation of the corresponding mechanistic pathways. The present review summarises recent studies in this field. To this end, the available complexes binding N2 and/or its intermediates on the pathway to ammonia are subdivided into systems containing early transition metals, Mo & W, iron and late transition metals. The implications of the findings obtained on low-molecular weight compounds with respect to the functionalisation of N2 and the reduction of N2 to ammonia on the FeMoco of nitrogenase are considered.