Structural Determination and Bonding Properties of Gas-Phase Ternary [O, Ta, 2C]- Anions.

A combined anion photoelectron spectroscopic and quantum chemical investigation was performed to explore the structures and bonding properties of ternary [O, Ta, 2C]- anions. The atomic bonding connectivity of the ternary anion was found to be (O-Ta-C2)- rather than (Ta-O-C2)-. The photoelectron spectrum using 266 nm photons was measured, and the theoretical simulated spectrum was calculated, with good agreement between experimental and theoretical results being found. Computations obtained electronic energies and low-energy structures and enabled chemical bonding analyses. The experimental vertical detachment energies of OTaC2- were measured to be 2.85 ± 0.08 eV. OTaC2- exhibits π aromaticity with two delocalized π electrons and σ antiaromaticity.