Trivalent acid radical-centered YLi4(+) (Y = PO4, AsO4, VO4) cations: new polynuclear species designed to enrich the superalkali family.

A new series of polynuclear superalkali cations YLi4(+) (Y = PO4, AsO4, VO4) has been characterized using ab initio methods. The central Y(3-) (PO4(3-), AsO4(3-), VO4(3-)) acid radicals preserve their structural and electronic integrity in the first several lowest-lying isomers of YLi4(+). Meanwhile, the introduction of Li(+) cations can also dissociate an O(2-) ion from the Y(3-) groups. Besides, the AsO4(3-) group is discerned to be separated into AsO2(-) and O2(2-) fragments other than AsO3(-) and O(2-) units. This is why the AsO4Li4(+) cation has been found to possess more diverse structures. The vertical electron affinities (EAvert) of the YLi4(+) cations range from 2.44 to 4.67 eV, which are low enough to validate the superalkali or pseudoalkali identity of the title species. It is also noteworthy that the YLi4(+) conformer with Td symmetry allows a more even distribution of the excess positive charge, and consequently exhibits the lowest EAvert value of ca. 2.45 eV.