Low ionization potentials of binuclear superalkali B2Li11

Abstract

A new type of binuclear superalkali B(2)Li(11) and its corresponding cation B(2)Li(11) (+) were theoretically predicted based on the density functional theory calculations. B(2)Li(11) was found to have six minimum energy structures corresponding to five cation states exhibiting superalkali nature. The global minima of B(2)Li(11) and B(2)Li(11) (+) are similar to each other in structure, where two central boron atoms directly link each other and the whole geometry resembles a capsule with an additional Li atom localized on its side. The vertical electron affinities for the B(2)Li(11) (+) cations at the OVGF/6-311+G(3df) level are in the range of 3.40-3.73 eV, which are lower than the ionization potential (IP) of Cs atom, and even lower than the IP=3.75 eV of the mononuclear superalkali BLi(6). Hence, the studied B(2)Li(11) (+) species should be classified as superalkali cations, and the B(2)Li(11) species can be regarded as superalkalies. Such binuclear superalkalies added candidates to the research on superatoms and offered potential building blocks for the assembly of new materials in which strong electron donors are involved. Note that the electronic shell structure of B(2)Li(11) is not consistent with the prediction of the cluster electronic shell model. It demonstrates that the doped nonmetal atoms make the molecular orbital-level distribution of heteronuclear species much more complex than that of homonuclear metal clusters.