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Interdependent Metal–Metal Bonding and Ligand Redox-Activity in a Series of Dinuclear Macrocyclic Complexes of Iron, Cobalt, and Nickel
- Source :
- Inorganic Chemistry; April 2020, Vol. 59 Issue: 7 p4200-4214, 15p
- Publication Year :
- 2020
-
Abstract
- This report describes an isostructural series of dinuclear iron, cobalt, and nickel complexes bound by a redox-active macrocyclic ligand. The series spans five redox levels (34–38 e–/cluster core), allowing for a detailed investigation into both the degree of metal–metal interaction and the extent of ligand-based redox-activity. Magnetometry, electrochemistry, UV–vis–NIR absorption spectroscopy, and crystallography were used in conjunction with DFT computational analyses to extract the electronic structures of the six homodinuclear complexes. The isoelectronic, 34 e–species [(3PDI2)Fe2(PMe3)2(μ-Cl)](OTf) and [(3PDI2)Co2(PMe3)2(μ-Cl)](OTf)3exhibit metal–metal single bonds, with varying amounts of electron density delocalization into the ligand as a function of the effective nuclear charge of the metal ions. One- and two-electron reductions of [(3PDI2)Co2(PMe3)2(μ-Cl)](OTf)3lead to isolable products, which show successive increases in both the Co–Co distances and the extent of reduction of the ligand manifold. This trend results from reduction of a Co–Co σ* orbital, which was found to be heavily mixed with the redox-active manifold of the 3PDI2ligand. A similar trend was observed in the 37 and 38 e–dinickel complexes [(3PDI2)Ni2(PMe3)2(μ-Cl)](OTf)2and [(3PDI2)Ni2(PMe3)2(μ-Cl)](OTf); however, their higher electron counts lead to high-spin ground states that result from occupation of a high-lying δ/δ* manifold with significant Ni–NPDIσ* character. This change in ground state configuration reforms a M–M bonding interaction in the 37 e–complex, but formation of the 38 e–species again disrupts the M–M bond alongside the transfer of electron density to the ligand.
Details
- Language :
- English
- ISSN :
- 00201669 and 1520510X
- Volume :
- 59
- Issue :
- 7
- Database :
- Supplemental Index
- Journal :
- Inorganic Chemistry
- Publication Type :
- Periodical
- Accession number :
- ejs51115421
- Full Text :
- https://doi.org/10.1021/acs.inorgchem.9b02339