Mechanochemical Synthesis, Characterization and Reactivity of a Room Temperature Stable Calcium Electride

Area of Science:

• Inorganic Chemistry
• Materials Science
• Solid-State Chemistry

Background:

• Electrides are ionic materials with electrons acting as anions.
• Calcium-based compounds offer unique electronic properties.
• Mechanochemical synthesis provides novel pathways for material discovery.

Purpose of the Study:

• To synthesize and characterize a new calcium-based Room temperature Stable Electride (RoSE).
• To investigate the electronic structure and magnetic properties of the synthesized electride.
• To explore the reactivity of the RoSE with organic molecules.

Main Methods:

• Mechanochemical synthesis of K[{Ca[N(Mes)(SiMe₃)]₃(e)}₂K₃] (2) from [Ca{N(Mes)(SiMe₃)}₃K] (1).
• Ab initio random structure searching (AIRSS) for structural elucidation.
• Electroconductivity measurements to determine electrical properties.
• Magnetometry to assess magnetic behavior.
• Reactions with pyridine and benzene to study chemical reactivity.
• Density Functional Theory (DFT) calculations for mechanistic insights.

Main Results:

• Successful synthesis of a new calcium-based RoSE, K[{Ca[N(Mes)(SiMe₃)]₃(e)}₂K₃] (2).
• AIRSS calculations confirmed a dimeric structure with localized anionic electrons (e).
• Poor electrical conductance and strong antiferromagnetic coupling of anionic electrons were observed.
• Reactions yielded 4,4'-bipyridine with pyridine and a calcium hydride complex with benzene via C-H activation.

Conclusions:

• The synthesized RoSE (2) possesses localized electrons and exhibits unique reactivity.
• The ligand framework plays a critical role in stabilizing the new calcium hydride complex.
• This study expands the understanding of electride chemistry and potential applications.