Synthesis, Structure, and Reactivity of a Magnesium(0) Complex with a Polarized Mgδ−─Caδ+ Bond

Thakur SK, Langer J, Roig N, Patro AG, Schmidt M, Alonso M, Harder S (2026)

Publication Type: Journal article

Publication year: 2026

Journal

DOI: 10.1002/anie.202525777

Abstract

Despite numerous examples of Mg─Mg bound complexes, complexes with unsupported two-center-two-electron Mg─Ca bonds so far always eluded their isolation. This is due to Mg^δ¯-Ca^δ+ polarization and their inherently very high reactivity resulting in oxidative addition to C─H bonds in either the ligand or solvent. Using a combination of bulky β-diketiminate (BDI*) and amidinate (Am*) ligands, we now present (BDI*)Mg-Ca(Am*); BDI* = HC[C(tBu)N(DIPeP)]2, DIPeP = 2,6-Et2C-phenyl; Am* = tBuC(N-DIPP)2, DIPP = 2,6-iPr-phenyl. The crystal structure shows a Mg─Ca bond of 3.298 Å and Mg/Ca NPA charges of +0.66/+1.28. This reflects considerable Mg^δ¯-Ca^δ+ polarization and is in line with the formal oxidation states Mg⁰-Ca^II. Effective-Oxidation-State (EOS) analysis confirms these formal oxidation states, but a low reliability index of 69.8% indicates that these are not fully representative for the electron distribution. Atoms-In-Molecules (AIM) shows a bond-critical-point on the Mg–Ca axis but a non-nuclear-attractor (NNA) was not observed. EDA-NOCV using two different fragmentations, (BDI*)Mgˉ/(Am*)Ca⁺ or (BDI*)Mg^●/(Am*)Ca^●, shows that the complex is best described as a combination of neutral radicals. The Mg⁰–Ca^II/Mg^I–Ca^I ambiguity results in a highly reactive Mg^δ¯─Ca^δ+ bond. This is confirmed by its reaction with CyN═C═NCy and Ph2C═CH2 showing the electrophilic nature of Ca and nucleophilic reactivity for Mg.

Authors with CRIS profile

Involved external institutions

Vrije Universiteit Brussel (VUB) Belgium (BE) University of Warwick United Kingdom (GB)

How to cite

APA:

Thakur, S.K., Langer, J., Roig, N., Patro, A.G., Schmidt, M., Alonso, M., & Harder, S. (2026). Synthesis, Structure, and Reactivity of a Magnesium(0) Complex with a Polarized Mgδ−─Caδ+ Bond. Angewandte Chemie International Edition. https://doi.org/10.1002/anie.202525777

MLA:

Thakur, Sandeep Kumar, et al. "Synthesis, Structure, and Reactivity of a Magnesium(0) Complex with a Polarized Mgδ−─Caδ+ Bond." Angewandte Chemie International Edition (2026).

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