Structural Evolution and Electronic Properties of TaSin-/0 (n=2-15) Clusters: Size-Selected Anion Photoelectron Spectroscopy and Theoretical Calculations

The structural evolution and electronic properties of TaSin-/0 (n = 2-15) clusters are explored using anion photoelectron spectroscopy accompanied by quantum chemical calculations. The Ta atom in TaSin-/0 is inclined to interact with more Si atoms and has high coordination numbers. The theoretical calculations show that TaSi2-/0 have trianglur structures and TaSin-/0 adopt pyramid structures, while the geometries of TaSin-/0 (n = 4-7) are all exohedral structures dominated by bipyramid-based configurations with the Ta atom face-capping the Si-n motifs. TaSi8-/0 and TaSi9-10- have boat-shaped geometries, whereas TaSi9-10 neutrals adopt bipyramid-based geometries instead of boat-shaped ones. TaSi11- and TaSi12 are confirmed as the critical size of transiting from exohedral to endohedral structures for anionic and neutral clusters, respectively. TaSi12-15-/0 have pentagonal or hexagonal prism-based geometries. Natural population analysis shows that the electron transfers from Si-n skeletons to Ta atom. The second-order energy differences (Delta E-2) and incremental binding energy (Delta E-1) values exhibit strong odd-even alternations, suggesting that the TaSin-odd-/0 clusters are more stable than the adjacent TaSi(n-even)(-/0 )ones, except that TaSi12-/0 are more stable than TaSi11-/0 and TaSi13-/0.