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Updated: Feb 14, 2026

Preparation of SNS CobaltII Pincer Model Complexes of Liver Alcohol Dehydrogenase
Published on: March 19, 2020
A Multifunctional Pincer Ligand for Cobalt-Promoted Oxidation by N2 O
Brian J Cook1, Chun-Hsing Chen1,2, Kenneth G Caulton1
1Department of Chemistry, Indiana University, 800 E Kirkwood Ave, Bloomington, IN, 47405, USA.
Abstract:
The divalent cobalt complex of the diprotic pincer ligand bis-pyrazolylpyridine, (H2 L)CoCl2 , is dehydrohalogenated twice by LiN(SiMe3 )2 in the presence of PEt3 to give monomeric S=1/2 LCo(PEt3 )2 (1), fully characterized in the solid-state and solution as a square pyramidal monomer with a long axial Co-P bond. This 17-electron species reacts in time of mixing with N2 O to form L2 Co2 (μ-OPEt3 ) (2)+3 OPEt3 , the former the first example of phosphine oxide bridging two transition metals. The same products are formed from O2 , and divalent cobalt persists even in the presence of excess oxidant. Species (2) catalyzes oxygen atom transfer (OAT) for generation of O=PEt3 from PEt3 from either N2 O or O2 . Bridging and terminal cobalt oxo intermediates are suggested, and the electron donor power, and potential redox activity of the dianionic pincer ligand is emphasized.
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