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

Ya-Ling Ye,Kai-Yun Pan,Bi-Lian Ni,Wei-Ming Sun

doi:10.3389/fchem.2022.853160

Abstract

In this study, to examine the possibility of using cage-like complexants to design nonmetallic superalkalis, a series of X@36adz (X = H, B, C, N, O, F, and Si) complexes have been constructed and investigated by embedding nonmetallic atoms into the 36adamanzane (36adz) complexant. Although X atoms possess very high ionization energies, these resulting X@36adz complexes possess low adiabatic ionization energies (AIEs) of 0.78–5.28 eV. In particular, the adiabatic ionization energies (AIEs) of X@36adz (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@36adz, this complex not only possesses pretty low AIE of 2.16 eV but also exhibits a remarkably large first hyperpolarizability (β 0) of 1.35 × 106 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.

Highlights

Reducing agents with low ionization energies (IEs) play a crucial role in chemical synthesis
It is interesting to find that the X@36adz (X = H, B, C, N, and Si) complexes possess lower adiabatic ionization energies (AIEs) values than the IE of Cs atoms though the X atoms and 36adz possess very high IE values
Thereby, they can be regarded as a new kind of nonmetallic superalkalis

Summary

INTRODUCTION

Reducing agents with low ionization energies (IEs) play a crucial role in chemical synthesis. Tkachenko et al (2019) reported the record low ionization potentials (1.70–1.52 eV) of alkali metal complexes with crown ethers and cryptands and defined them as superalkali species. Such alkali metal complexes were previously named as electrides, a special kind of ionic solids with trapped electrons serving as anions (Dye, 2009). Under the repulsion of the lone pairs of N atoms, the outmost valence electrons of X are destabilized to different degrees, leading to the obvious rise of HOMO level of X@36adz as compared with the isolated 36adz complexant As a result, these proposed complexes exhibit extraordinarily low AIE values of 0.78–5.28 eV X atoms possess very high ionization energies (IEs) of 8.15–17.42 eV (Lide, 2003). The dimensional plots of the molecular structures were generated with the GaussView program (Dennington et al, 2016)

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT