Structural Determination and Bonding Characteristics of the Gas-Phase Ta2Si2̅ Anion and Its Neutral: Anion Photoelectron Spectroscopy and Theoretical Studies

The structures and bonding characteristics of Ta2Si2̅/0 clusters are investigated using anion photoelectron spectroscopy and quantum chemical calculations. The vertical detachment energy of the Ta2Si2̅ anion is measured to be 2.00 ± 0.08 eV using the 266 nm photon. It is found that the Ta2Si2̅ anion has three low-energy isomers with a C2v symmetric Ta–Ta dibridged structural framework, all of which contribute to the experimental photoelectron spectrum, while the Ta2Si2 neutral also has a C2v symmetric Ta–Ta dibridged structural framework. The charge-transfer from Ta atoms to Si atoms is discovered using atomic dipole moment corrected Hirshfeld analysis for the Ta2Si2̅ anion and Ta2Si2 neutral. Chemical bonding investigations show that both the Ta2Si2̅ anion and Ta2Si2 neutral have a strong covalent Ta–Ta bond, as well as σ and π double bonding patterns. Furthermore, the Ta atoms are linked together by a single 2c–2e Ta2 σ bond, whereas the Si atoms are linked together with the Ta atoms via four 2c–2e TaSi σ bonds, two 3c–2e TaSi2 σ bonds, one 4c–2e Ta2Si2 σ bond, and one 4c–2e Ta2Si2 π bond.