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

Alex W.J. Bowles; James A. Quirk; Yu Liu; George H. Morritt; Marina Freitag; George F. S. Whitehead; Adam W. Woodward; Adam Brookfield; Conrad A. P. Goodwin; David Collison; Floriana Tuna; Claire L. McMullin; James A. Dawson; Erli Lu; Fabrizio Ortu

doi:10.1021/jacs.4c09408

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

Alex W.J. Bowles, James A. Quirk, Yu Liu, George H. Morritt, Marina Freitag, George F. S. Whitehead, Adam W. Woodward, Adam Brookfield, Conrad A. P. Goodwin, David Collison, Floriana Tuna^*, Claire L. McMullin^*, James A. Dawson^*, Erli Lu^*, Fabrizio Ortu^*

^*Corresponding author for this work

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Abstract

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.

Original language	English
Pages (from-to)	28914-28924
Number of pages	11
Journal	Journal of the American Chemical Society
Volume	146
Issue number	42
Early online date	8 Oct 2024
DOIs	https://doi.org/10.1021/jacs.4c09408
Publication status	Published - 23 Oct 2024

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Bowles, A. W. J., Quirk, J. A., Liu, Y., Morritt, G. H., Freitag, M., Whitehead, G. F. S., Woodward, A. W., Brookfield, A., Goodwin, C. A. P., Collison, D., Tuna, F., McMullin, C. L., Dawson, J. A., Lu, E., & Ortu, F. (2024). Mechanochemical Synthesis, Characterization and Reactivity of a Room Temperature Stable Calcium Electride. Journal of the American Chemical Society, 146(42), 28914-28924. https://doi.org/10.1021/jacs.4c09408

@article{ffc7b6d679624d1cb55188c433d81150,

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

abstract = "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.",

author = "Bowles, {Alex W.J.} and Quirk, {James A.} and Yu Liu and Morritt, {George H.} and Marina Freitag and Whitehead, {George F. S.} and Woodward, {Adam W.} and Adam Brookfield and Goodwin, {Conrad A. P.} and David Collison and Floriana Tuna and McMullin, {Claire L.} and Dawson, {James A.} and Erli Lu and Fabrizio Ortu",

year = "2024",

month = oct,

day = "23",

doi = "10.1021/jacs.4c09408",

language = "English",

volume = "146",

pages = "28914--28924",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",

publisher = "American Chemical Society",

number = "42",

}

Bowles, AWJ, Quirk, JA, Liu, Y, Morritt, GH, Freitag, M, Whitehead, GFS, Woodward, AW, Brookfield, A, Goodwin, CAP, Collison, D, Tuna, F, McMullin, CL, Dawson, JA, Lu, E & Ortu, F 2024, 'Mechanochemical Synthesis, Characterization and Reactivity of a Room Temperature Stable Calcium Electride', Journal of the American Chemical Society, vol. 146, no. 42, pp. 28914-28924. https://doi.org/10.1021/jacs.4c09408

TY - JOUR

T1 - Mechanochemical Synthesis, Characterization and Reactivity of a Room Temperature Stable Calcium Electride

AU - Bowles, Alex W.J.

AU - Quirk, James A.

AU - Liu, Yu

AU - Morritt, George H.

AU - Freitag, Marina

AU - Whitehead, George F. S.

AU - Woodward, Adam W.

AU - Brookfield, Adam

AU - Goodwin, Conrad A. P.

AU - Collison, David

AU - Tuna, Floriana

AU - McMullin, Claire L.

AU - Dawson, James A.

AU - Lu, Erli

AU - Ortu, Fabrizio

PY - 2024/10/23

Y1 - 2024/10/23

N2 - 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.

AB - 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.

U2 - 10.1021/jacs.4c09408

DO - 10.1021/jacs.4c09408

M3 - Article

SN - 0002-7863

VL - 146

SP - 28914

EP - 28924

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 42

ER -

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

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