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A Multifunctional Pincer Ligand for Cobalt‐Promoted Oxidation by N 2 O
Author(s) -
Cook Brian J.,
Chen ChunHsing,
Caulton Kenneth G.
Publication year - 2018
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.201800086
Subject(s) - cobalt , chemistry , ligand (biochemistry) , pincer ligand , pincer movement , divalent , medicinal chemistry , monomer , redox , phosphine , phosphine oxide , electron transfer , bridging ligand , crystallography , stereochemistry , polymer chemistry , inorganic chemistry , photochemistry , crystal structure , organic chemistry , catalysis , polymer , biochemistry , receptor
The divalent cobalt complex of the diprotic pincer ligand bis‐pyrazolylpyridine, (H 2 L)CoCl 2 , is dehydrohalogenated twice by LiN(SiMe 3 ) 2 in the presence of PEt 3 to give monomeric S =1/2 LCo(PEt 3 ) 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 N 2 O to form L 2 Co 2 (μ‐OPEt 3 ) ( 2 )+3 OPEt 3 , the former the first example of phosphine oxide bridging two transition metals. The same products are formed from O 2 , and divalent cobalt persists even in the presence of excess oxidant. Species ( 2 ) catalyzes oxygen atom transfer (OAT) for generation of O=PEt 3 from PEt 3 from either N 2 O or O 2 . Bridging and terminal cobalt oxo intermediates are suggested, and the electron donor power, and potential redox activity of the dianionic pincer ligand is emphasized.