Reaction of Ta(3)(–) Clusters with Molecular Nitrogen: A Mechanism Investigation

[Image: see text] Because of the inertness of molecular nitrogen, its practicable activation under mild conditions is a fundamental challenge. Ta(3)(–) is an exceptionally small cluster that reacts with N(2) at room temperature, leading finally to Ta(3)N(2)(–); Ta(3)N(2)(–) also could react with N(2) at room temperature, leading finally to Ta(3)N(4)(–), a product of interest in its own right because of its potential as a nitrogen fixation medium. The mechanisms of the Ta(3)(–)- and Ta(3)N(2)(–)-mediated activation of the N≡N triple bond have been investigated. Our extensive computations elucidate mechanisms for the ready reactions, leading to stepwise cleavage of the N≡N bond. Initial isomeric N(2)/Ta(3)(–) complexes, N≡N elongation, undergo a N≡N split over generally low barriers in a highly exothermic process. The nitrogen-atom or molecular exchange reactions found in the Ta(3)N(2)(–)/N(2) system may be of paramount importance in both applied and fundamental studies.