# Dinitrogen Splitting without Barrier or Visible Light‐Driven: Reactions of Vanadium Trimers and Dimers with Dinitrogen

## TL;DR

Vanadium clusters can split dinitrogen without needing a catalyst or visible light, forming nitride clusters with unique structures.

## Contribution

Vanadium trimers split dinitrogen spontaneously, while dimers require visible light and form isomeric nitride clusters.

## Key findings

- Vanadium trimers (V3) immediately split N2 without visible light to form V3N2 clusters.
- Vanadium dimers (V2) require visible light to form two isomeric V2N2 clusters.
- Vanadium atoms only form weak N2 complexes without bond cleavage.

## Abstract

The reaction of V atoms and small clusters with dinitrogen has been investigated by matrix isolation in solid Ne and by complementary quantum chemical calculations. The experiments disclose striking differences between the reactivity of V atoms, dimers, and trimers toward dinitrogen. Whereas V atoms react only by formation of complexes, both V2 and V3 react by cleavage of the N2 triple bond to form nitride clusters. Whereas V3 reacts immediately at the conditions of matrix deposition, the reaction of V2 requires activation by irradiation with visible light. There is evidence for two isomers of V2N2, a planar one with a 5Au electronic term and a long V─V distance, and a folded one with a 1A1 term and a short V─V distance. Furthermore, there are also complexes of V2 and V3 with N2 that contain activated N2 units.

Striking differences between the reactivity of vanadium atoms, dimers, and trimer clusters were revealed by matrix isolation experiments. Vanadium atoms only form weakly bound N2 complexes, but the V3 cluster splits the NN triple bond to give a V3N2 cluster. The V2 dimer requires visible light irradiation to form two isomeric V2N2 clusters with and without V─V bond. The results demonstrate the potential of clusters for N2 conversion.