Designing Special Nonmetallic Superalkalis Based on a Cage-like Adamanzane Complexant.

In this study, to examine the possibility of using cage-like complexants to design nonmetallic superalkalis, a series of X@3adz (X = H, B, C, N, O, F, and Si) complexes have been constructed and investigated by embedding nonmetallic atoms into the 3adamanzane (3adz) complexant. Although X atoms possess very high ionization energies, these resulting X@3adz complexes possess low adiabatic ionization energies (AIEs) of 0.78-5.28 eV. In particular, the adiabatic ionization energies (AIEs) of X@3adz (X = H, B, C, N, and Si) are even lower than the ionization energy (3.89 eV) of Cs atoms, and thus, can be classified as novel nonmetallic superalkalis. Moreover, due to the existence of diffuse excess electrons in B@3adz, this complex not only possesses pretty low AIE of 2.16 eV but also exhibits a remarkably large first hyperpolarizability ( ) of 1.35 × 10 au, indicating that it can also be considered as a new kind of nonlinear optical molecule. As a result, this study provides an effective approach to achieve new metal-free species with an excellent reducing capability by utilizing the cage-like organic complexants as building blocks.