15-Crown-5-based metalides: computational insights into excess electrons and enhanced NLO response

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Explores a new class of metalide complexes based on 15-crown-5.
• Investigates alkali metal (AM+) and transition metal (TM-) combinations (Li-K and Zn-Hg).
• Assesses the nonlinear optical (NLO) properties of these novel complexes.

Purpose of the Study:

• To evaluate the electronic and thermodynamic stability of designed metalide complexes.
• To validate the metalide nature using advanced computational methods.
• To determine the NLO response, including polarizability and hyperpolarizability, and the effect of external electric fields.

Main Methods:

• Density Functional Theory (DFT) calculations using ωB97X-D functional.
• Employed 6-31+G(d,p) and LANL2DZ basis sets.
• Analyzed electronic properties and geometries using Gaussian 16, GaussView 6.0, and Multiwfn software.

Main Results:

• All complexes demonstrated electronic and thermodynamic stability (IP: 2.18–2.95 eV, E_int: -129.89 to -214.89 kcal/mol).
• Metalide nature confirmed via NBO, FMO, MESP, ELF, and PDOS analyses.
• Li+(15-c-5)Hg- exhibited highest NLO response (β₀: 1.08×10⁶ a.u., α₀: 1022 a.u.).
• External electric fields significantly enhanced NLO properties, with β₀ increasing to 2.56×10⁶ a.u. for Li+(15-c-5)Hg- under a positive field.

Conclusions:

• Metalide complexes based on 15-crown-5 show promising stability and significant NLO characteristics.
• The NLO response can be further tuned by applying external electric fields.
• These findings suggest metalides are potential candidates for next-generation NLO materials.