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

• DOI: 10.1021/jacs.4c09408
• Publication Date: 2024-10-08T16:13:44Z
• Authors: Alex W. J. Bowles; James A. Quirk; Yu Liu; George H. Morritt; Marina Freitag; George F. S. Whit...; Adam W. Woodward; Adam Brookfield; Conrad A. P. Goodwin; David Collison; Floriana Tuna; Claire L. McMullin; James A. Dawson; Erli Lu; Fabrizio Ortu

A new calcium-based Room temperature Stable Electride (RoSE), K[{Ca[N(Mes)(SiMe3)]3(e-)}2K3] (2), is successfully synthesized from the reaction of a calcium tris-amide, [Ca{N(Mes)(SiMe3)}3K] (1) (Mes = 2,4,6-trimethylphenyl), with potassium under mechanochemical treatment. The dimeric structure of K[{Ca[N(Mes)(SiMe3)]3(e-)}2K3] is calculated using ab initio random structure searching (AIRSS) methods. This shows the existence of highly localized anionic electrons (e-) and suggests poor electrical conductance, as confirmed via electroconductivity measurements. The two anionic electrons in 2 are strongly antiferromagnetically coupled, thus in agreement with the largely diamagnetic response from magnetometry. Reaction of 2 with pyridine affords 4,4'-bipyridine, while reaction with benzene gives C-H activation and formation of a calcium hydride complex, [K(η6-C6H6)4][{Ca[N(Mes)(SiMe3)](H)}2K3] (3). Computational DFT analysis reveals the crucial role played by the ligand framework in the stabilization of this new Ca-hydride complex.