A Multifunctional Pincer Ligand for Cobalt-Promoted Oxidation by N2O

作者：Cook Brian J; Chen Chun Hsing; Caulton Kenneth G^*

来源：Chemistry - A European Journal, 2018, 24(22): 5962-5966.

DOI：10.1002/chem.201800086

• cobalt
• homogeneous catalysis
• nitrogen oxides
• oxidation
• pincer ligands

The divalent cobalt complex of the diprotic pincer ligand bis-pyrazolylpyridine, (H2L)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 N2O to form L2Co2(mu-OPEt3) (2) + 3 OPEt3, 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=PEt3 from PEt3 from either N2O 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.

• 出版日期2018-4-17