Cook Brian J, Chen Chun-Hsing, Caulton Kenneth G
Department of Chemistry, Indiana University, 800 E Kirkwood Ave, Bloomington, IN, 47405, USA.
Molecular Structure Center, Indiana University, 800 E Kirkwood Ave, Bloomington, IN, 47405, USA.
Chemistry. 2018 Apr 17;24(22):5962-5966. doi: 10.1002/chem.201800086. Epub 2018 Mar 23.
The divalent cobalt complex of the diprotic pincer ligand bis-pyrazolylpyridine, (H L)CoCl , is dehydrohalogenated twice by LiN(SiMe ) in the presence of PEt to give monomeric S=1/2 LCo(PEt ) (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 O to form L Co (μ-OPEt ) (2)+3 OPEt , the former the first example of phosphine oxide bridging two transition metals. The same products are formed from O , and divalent cobalt persists even in the presence of excess oxidant. Species (2) catalyzes oxygen atom transfer (OAT) for generation of O=PEt from PEt from either N O or O . Bridging and terminal cobalt oxo intermediates are suggested, and the electron donor power, and potential redox activity of the dianionic pincer ligand is emphasized.
双质子钳形配体双吡唑基吡啶的二价钴配合物（HL）CoCl，在PEt存在下被LiN(SiMe)进行两次脱卤化氢反应，生成单体S = 1/2的LCo(PEt)（1），在固态和溶液中被充分表征为具有长轴向Co-P键的四方锥单体。这种17电子物种在混合时与N O反应形成L Co (μ-OPEt )（2）+ 3OPEt，前者是氧化膦桥连两个过渡金属的首个例子。由O也能形成相同产物，即使在存在过量氧化剂的情况下二价钴仍能存在。物种（2）催化氧原子转移（OAT），用于从N O或O的PEt生成O = PEt。文中提出了桥连和末端钴氧中间体，并强调了双阴离子钳形配体的给电子能力和潜在的氧化还原活性。
