Structures of [CoO(CO₂)_<i>n</i>]⁻ and [NiO(CO₂)_<i>n</i>]⁻ Clusters Studied by Infrared Spectroscopy

We present infrared spectra of [CoO­(CO₂)_<i>n</i>]⁻ and [NiO­(CO₂)_<i>n</i>]⁻ clusters and interpret them in the framework of computational results employing density functional theory. We find that both [CoO­(CO₂)_<i>n</i>]⁻ and [NiO­(CO₂)_<i>n</i>]⁻ clusters are generally composed of the same core isomers. The dominant isomers consist of an η² CO₂ ligand and a CO₃ moiety that can be bound to the metal atom with monodentate (η¹) or bidentate (η²) connectivity. Minor structural isomers observed are composed of a C₂O₄ moiety with a lone oxygen atom or a CO₃ unit