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Noninnocent β‐Diiminate Ligands: Redox Activity of a Bis(alkylimidazole)methane Ligand in Cobalt and Zinc Complexes
Author(s) -
Ghosh Pradip,
Naastepad Richard,
Riemersma Charl F.,
Lutz Martin,
Moret MarcEtienne,
Klein Gebbink Robertus J. M.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201701215
Subject(s) - ligand (biochemistry) , chemistry , cobalt , zinc , imidazole , redox , medicinal chemistry , crystal structure , stereochemistry , crystallography , inorganic chemistry , organic chemistry , receptor , biochemistry
Abstract A new β‐diiminate ligand (the bis(1‐methyl‐4,5‐diphenyl‐1 H ‐imidazol‐2‐yl)methane anion, BMIM Ph2− ) is introduced, in which the ligand framework bears an extended imidazole‐based π‐system in conjugation with a formal β‐diketiminates (NacNac) backbone. Bis‐ligated transition metal complexes (Co, Zn) featuring this anionic ligand undergo a series of four consecutive single‐electron oxidations that are all ligand‐based. The singly and doubly oxidized complexes can be synthesized on a preparative scale and have been fully characterized by various spectroscopic techniques. This is in sharp contrast to the corresponding NacNac‐based complexes in which only singly oxidized complexes were isolated and characterized. Single crystal X‐ray structure determination revealed a correlation between the intra‐ligand metrical parameters and the oxidation state of BMIM Ph2− . These structural changes in the ligand framework make BMIM Ph2− as a perceptible non‐innocent ligand in contrast to NacNac type ligands.