Structural Determination and Bonding Characteristics of the Gas-Phase Ta 2 Si 2 ̅ Anion and Its Neutral: Anion Photoelectron Spectroscopy and Theoretical Studies.

The structures and bonding characteristics of Ta 2 Si 2 ̅ /0 clusters are investigated using anion photoelectron spectroscopy and quantum chemical calculations. The vertical detachment energy of the Ta 2 Si 2 ̅ anion is measured to be 2.00 ± 0.08 eV using the 266 nm photon. It is found that the Ta 2 Si 2 ̅ anion has three low-energy isomers with a C 2v symmetric Ta-Ta dibridged structural framework, all of which contribute to the experimental photoelectron spectrum, while the Ta 2 Si 2 neutral also has a C 2v 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 Ta 2 Si 2 ̅ anion and Ta 2 Si 2 neutral. Chemical bonding investigations show that both the Ta 2 Si 2 ̅ anion and Ta 2 Si 2 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 Ta 2 σ bond, whereas the Si atoms are linked together with the Ta atoms via four 2c-2e TaSi σ bonds, two 3c-2e TaSi 2 σ bonds, one 4c-2e Ta 2 Si 2 σ bond, and one 4c-2e Ta 2 Si 2 π bond.