Photoelectron spectroscopy and formation mechanism of Ta2N3−: Activation of N2 by Ta2N−

This work investigated the reaction mechanism of N2 on Ta2N- via the photoelectron spectroscopy study of Ta2N3-, focusing on the activation of nitrogen molecules (N2) by Ta2N-. The vertical detachment energy of Ta2N3- was determined to be 2.22 eV from the experimental photoelectron spectrum. Charge and bond order analyses reveal significant electron transfer from Ta to N and strong Ta-N bonding, supporting the relative stability and reactivity of the cluster. Energy decomposition analysis and natural orbitals for chemical valence analysis show that orbital interactions, especially π- and σ-donations from Ta2N- to N2, dominate the activation process of N2. Substantial charge transfer occurs from the Ta2N- fragment to the N2 fragment, accompanied by noticeable polarization, which facilitates the breaking of the N≡N bond. The results highlight the importance of Ta-N bond coordination in stabilizing dissociated nitrogen atoms, making Ta2N- a potentially efficient species for N2 activation.