Cyclometalated Organonickel Complexes through C-H and C-X Activation

通过C-X或C-H键活化和三齿配体的C供体官能团的金属化，将从Ni（0）或Ni（II）前体合成具有阴离子三齿CNN或NCN配体的新型环化有机镍（II）配合物。将探索几种潜在的机理变化：（a）将原配体C-X官能团氧化加成到Ni（0）前体络合物上，（B）C-H去质子化并结合到Ni（II）上，（c）将C-H氧化加成到Ni（0）或Ni（II）上，以及（d）从C-H或C-X官能化的原配体和Ni（II）开始电化学诱导的C-Ni偶联;推测涉及自由基步骤。虽然C-X氧化加成到Ni（0）是一个既定的程序，并且先前已经报道了通过去质子化的C-H活化，但Ni（0）的C-H活化代表了一个很大的挑战，并且电化学诱导的程序是前所未有的。新的环化配合物，也是原配体和复杂的前体将分析，光谱和电化学特征，探索空间和电子的先决条件，一个成功的环化反应和环化配合物和非环化衍生物之间的差异。量子化学计算将有助于理解。C-H和C-X活化的这项研究将允许详细了解C-C偶联催化的关键步骤之一，以及作为关键中间体的环化有机镍配合物的结构和电子学。

New cyclometalated organonickel(II) complexes with anionic tridentate CNN or NCN ligands will be synthesised from Ni(0) or Ni(II) precursors through C-X or C-H bond activation and metalation of the C donor function of the tridentate ligands. Several potential mechanistic variations will be explored: (a) Oxidative addition of proto-ligand C-X functions to Ni(0) precursor complexes, (b) C-H deprotonation and binding to Ni(II), (c) oxidative addition of C-H to Ni(0) or Ni(II), and (d) electrochemically induced C-Ni coupling starting from C-H or C-X functionalised proto-ligands and Ni(II); presumably involving radical steps. While C-X oxidative addition to Ni(0) is an established procedure and the C-H activation through deprotonation has been previously reported, the C-H activation by Ni(0) represents a big challenge and electrochemically induced procedures are unprecedented. The new cyclometalated complexes and also the proto-ligands and complex precursors will be analytically, spectroscopically and electrochemically characterised to explore the steric and electronical prerequisites for a successful cyclometalation reaction and the differences between cyclometalated complexes and non-cyclometalated derivatives. Quantum chemical calculations will add to the understanding. This study on C-H and C-X activation will allow detailed insight into one of the key steps of C-C coupling catalysis and into the structure and electronics of such cyclometalated organonickel complexes as key intermediates.