Superalkali Li₃ dissolved in gaseous ammonia is investigated by density functional theory. Similar to the lithium atom, Li₃ can coordinate up to four ammonia molecules. Among the structural isomers of Li₃(NH₃)_n (n = 1–4), the one with separately distributed NH₃ ligands is preferred. Most of the Li₃(NH₃)_n species possess the alkalide characteristics and exhibit considerably large static first hyperpolarizabilities (β₀) up to 3.9 × 10⁵ au. Especially, for the lowest-energy Li₃(NH₃)_n complexes, a prominent coordination number dependence of β₀ is found as follows: 12 608 (n = 1) < 38 564 (n = 2) < 121 726 (n = 3) < 391 149 au (n = 4). In addition, the case of introducing a Na atom into such superalkali–ammonia systems has been considered and the resulting Li₃(NH₃)_nNa (n = 1–4) complexes are studied in the same vein. It is revealed that the β₀ values of Li₃(NH₃)_nNa are influenced by both the coordination number and the relative position of NH₃ ligands. We hope that this study could provide a new type of alkalides and raise the possibility of exploring a fresh, thriving area, i.e. superalkali solutions with solvents of all sorts.

A series of novel excess electron compounds M(NH₃)₆NaCl and M(NH₃)₆Na₂ (M = Mg and Ca) were designed, in which the lowest-energy M(NH₃)₆Na₂ compounds are the first alkalides containing double alkali metal anions.

A new series of polynuclear superalkali cations YLi₄⁺(Y = PO4, AsO4, VO4) has been designed and characterized to enrich the superalkali family.

The geometries of the MBeX₃ (M = Li, Na; X = F, Cl, Br) series with all real frequencies are reported using the B3LYP and MP2 methods with the 6-311+G(d) basis set. The natural bond orbital (NBO) and atom in molecule (AIM) analyses indicate the ionic character of the M–X bonds connecting the alkali atom M and the superhalogen BeX₃. The introduction of a counterion M⁺ only slightly affects the geometry of BeX₃ ⁻, but produces a more stable species. The bond energies (E_b) and vertical ionization potentials (VIP) of the MBeX₃ species are obtained at the CCSD(T)/6-311+G(3df) level. These alkali–superhalogen species exhibit large E_b (130.4–222.3 kcal mol⁻¹) and VIP values (9.46–14.05 eV) to show considerable stabilities. In addition, both E_bs and VIPs of MBeX₃ are found to be closely related to the electronegativity of the X ligands and partial atomic charges.