Octahedral Coordinated Cluster TaN ₁₂ ⁺ : Mass Spectrometry Detection, Photodissociation Observation, and Theoretical Exploration

The TaN_n ⁺ cationic clusters were generated via laser ablation and analyzed using time-of-flight (TOF) mass spectrometry. The mass spectrometry experiment identified the TaN₁₂ ⁺ cluster as the dominant TaN compound, exhibiting the most intense peak. Photodissociation experiments on the TaN₁₂ ⁺ clusters with 266 nm (4.66 eV) photons revealed that the photodissociation fragment ion TaN₄ ⁺ was dominant in the spectrum. Density functional theory calculations revealed that TaN₁₂ ⁺ has an octahedral D_4h geometry symmetry with six N₂ ligands. The cluster features two distinct TaN bond lengths of 2.16 and 2.22 Å. Orbital analysis uncovers the origin of this asymmetry: the four coplanar N₂ ligands are strongly σ-bound and activated, whereas the two axial ones engage via weaker π-interactions. Photodissociation pathway analysis established a reversible relationship between TaN_2n ⁺ (n = 1 - 6) clusters growth-dissociation processes. Quantitative Hirshfeld charge and charge transfer analyses confirm Ta as a Lewis acid center with N₂ ligands functioning as Lewis bases. The spin-density population indicates the presence of antiparallel coupling within the TaN₁₂ ⁺ cluster, leading to ferrimagnetism. Interaction region indicator analysis confirms the presence of well-defined coordination bonds between the Ta atom and its ligands.