Access to a Labile Monomeric Magnesium Radical by Ball-Milling

Jedrzkiewicz D, Mai J, Langer J, Mathe Z, Patel N, DeBeer S, Harder S (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Angewandte Chemie International Edition Wiley

DOI: 10.1002/anie.202200511

Abstract

In order to isolate a monometallic Mg radical, the precursor (Am)MgI⋅(CAAC) (1) was prepared (Am=tBuC(N-DIPP)2, DIPP=2,6-diisopropylphenyl, CAAC=cyclic (alkyl)(amino)carbene). Reduction of a solution of 1 in toluene with the reducing agent K/KI led to formation of a deep purple complex that rapidly decomposed. Ball-milling of 1 with K/KI gave the low-valent Mg^I complex (Am)Mg⋅(CAAC) (2) which after rapid extraction with pentane and crystallization was isolated in 15 % yield. Although a benzene solution of 2 decomposes rapidly to give Mg(Am)2 (3) and unidentified products, the radical is stable in the solid state. Its crystal structure shows planar trigonal coordination at Mg. The extremely short Mg−C distance of 2.056(2) Å indicates strong Mg−CAAC bonding. Calculations and EPR measurements show that most of the spin density is in a π* orbital located at the C−N bond in CAAC, leading to significant C−N bond elongation. This is supported by calculated NPA charges in 2: Mg +1.73, CAAC −0.82. Similar metal-to-CAAC charge transfer was calculated for M⁰(CAAC)2 and [M^I(CAAC)2⁺] (M=Be, Mg, Ca) complexes in which the metal charges range from +1.50 to +1.70. Although the spin density of the radical is mainly located at the CAAC ligand, complex 2 reacts as a low-valent Mg^I complex: reaction with a I2 solution in toluene gave (Am)MgI⋅(CAAC) (1) as the major product.

Authors with CRIS profile

Dawid Jedrzkiewicz Lehrstuhl für Anorganische und Metallorganische Chemie Jonathan Mai Lehrstuhl für Anorganische und Metallorganische Chemie Jens Langer Lehrstuhl für Anorganische und Metallorganische Chemie Neha Patel Lehrstuhl für Anorganische und Metallorganische Chemie Sjoerd Harder Lehrstuhl für Anorganische und Metallorganische Chemie

Involved external institutions

Max-Planck-Institut für Chemische Energiekonversion (MPI CEC) / Max-Planck-Institute for Chemical Energy Conversion

Germany (DE)

How to cite

APA:

Jedrzkiewicz, D., Mai, J., Langer, J., Mathe, Z., Patel, N., DeBeer, S., & Harder, S. (2022). Access to a Labile Monomeric Magnesium Radical by Ball-Milling. Angewandte Chemie International Edition. https://dx.doi.org/10.1002/anie.202200511

MLA:

Jedrzkiewicz, Dawid, et al. "Access to a Labile Monomeric Magnesium Radical by Ball-Milling." Angewandte Chemie International Edition (2022).

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