Prediction and characterization of novel polynuclear superalkali cations

Abstract

A series of polynuclear superalkali cations YLi₃⁺ (Y = O₂, CO₄, C₂O₄, and C₂O₆) have been studied using ab initio method. The structural characters and stabilities of these systems are found to be related to the nature of the central cores. In the lowest-energy structure of the C₂O₄Li₃⁺ cations, the central group features a slight distortion. While in the global minima of O₂Li₃⁺, CO₄Li₃⁺ and C₂O₆Li₃⁺ cations, the central cores are divided into various units including one peroxo group (O₂). These YLi₃⁺ (Y = O₂, CO₄, C₂O₄, and C₂O₆) species exhibit very low vertical electron affinities of 3.01–3.85 eV (except one outlier in one of the O₂Li₃⁺ species which lie much higher in energy than the most stable structure) and hence should be classified as superalkali cations, and the corresponding neutral species can be regarded as superalkalies. Such polynuclear superalkalies are candidates to the superatoms and offered potential building blocks for the assembly of new materials in which strong electron donors are involved.