Structure determination and bonding properties of gas-phase OPt₂^- anion and its neutral form

Using anion photoelectron spectroscopy and quantum chemical calculations, the structures and properties of OPt₂^-/0 are investigated. The vertical detachment energies (VDEs) of OPt₂^- are measured to be 3.28 eV and 3.23 eV through the use of 355 and 266 nm photons, respectively. The high experimental VDEs of OPt₂^- can be attributed to the strong Pt-Pt and Pt-O σ bonds and low orbital energy of the SOMO. It is found that neutral OPt₂ has an OPt₂ triangular structure with C_2v symmetry and ¹A₁ electronic state. In the neutral OPt₂, the O atom interacts with the Pt₂ moiety by two 2c-2e PtO bonds, one 3c-2e Pt₂O σ bond, and one 3c-2e Pt₂O π bond. On the other hand, anionic OPt₂ adopts a Pt-Pt-O bent structure with C_s symmetry and ²A' electronic state. NPA and ELF analyses indicate charge transfer upon complexation from the metal atoms to the O atom. Chemical bonding analyses show that OPt₂^-/0 have the strong covalent Pt-Pt and Pt-O bonds, and neutral OPt₂ exhibits σ aromaticity and π antiaromaticity.