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Leveraging Chelating Amido Ligands to Support Metal-Metal Bonding in Dinuclear Cr(II) Complexes
Journal article   Open access   Peer reviewed

Leveraging Chelating Amido Ligands to Support Metal-Metal Bonding in Dinuclear Cr(II) Complexes

Janadhi L Ananda Nakath Durage, Joan Cardona, Soumen Sinhababu, Darby H Duffy, Daniel Martinez, Matthew P Shores, Daniel K Unruh, Bess Vlaisavljevich and Scott R Daly
Inorganic chemistry
03/05/2026
DOI: 10.1021/acs.inorgchem.6c00424
PMCID: PMC12997166
PMID: 41784549
url
https://doi.org/10.1021/acs.inorgchem.6c00424View
Published (Version of record) Open Access

Abstract

Herein, we report a series of Cr(II) complexes containing triaryl, tetradentate ligands derived from o-phenylenediamide that illuminate how rigid, chelating amido ligands facilitate Cr–Cr bonding. The aminolysis reaction of Cr[N(SiMe3)2]2(thf)2 with H2(L1)─a protonated N4 proligand containing flanking NMe2 groups─yielded square planar and mononuclear Cr(L1) (1), whereas the same reaction with N2S2 and N2O2 proligands with flanking SMe and OMe groups yielded dinuclear [Cr(L2)]2 (2) and [Cr(L3)]2 (3). The structures of 2 and 3 revealed Cr–Cr distances of 2.3356(6) and 2.3481(5) Å, consistent with metal–metal bonding, which was confirmed by the complete active space methods. The theoretical results suggest that Cr–Cr bonding is assisted by the chelating nature of the bridging amido ligands, which fold the dinuclear structure and orient the metals so that side-on overlap of Cr 3d orbitals can occur. Variable-temperature SQUID magnetometry and spectroscopic data (e.g., UV–vis-NIR, Raman, and IR) reported for 1–3 show differences indicative of the change in nuclearity and electronic structure. Collectively, these results reveal bridging amido ligand characteristics that support metal–metal bonding with Cr(II), and they help account for the wide range of metal–metal distances observed in dinuclear (or binuclear) Cr(II) complexes containing Cr2N2 cores.

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