Cyclometalated Ni(II) Complexes [Ni(N∧C∧N)X] of the Tridentate 2,6-di(2-pyridyl)phen-ide Ligand
Cyclometalated Ni(II) Complexes [Ni(N∧C∧N)X] of the Tridentate 2,6-di(2-pyridyl)phen-ide Ligand
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DOI：
10.1021/acs.organomet.0c00355
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发表时间：
2020-07
期刊：
影响因子：
2.8
通讯作者：
Lukas Kletsch;G. Hörner;A. Klein
中科院分区：
文献类型：
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作者：
Lukas Kletsch;G. Hörner;A. Klein
研究了一系列以N <$C <$N-三齿阴离子配体Py <$（Ph-）<$Py 2，6-二（2-吡啶基）邻苯二甲酰化物（Py <$（HPh）<$Py = 1，3-二（2-吡啶基）邻苯二甲酰化物）和X = Cl、Br或I为共配体的环化镍配合物[Ni <$（PyPhPy）<$X].在非极性高沸点溶剂中，以KOAc/K_2CO_3为催化剂，NiX_2和Py_xO（HPh）_xO（Py）为配体，通过C-H碱辅助直接镍化反应，得到了三种配合物。虽然整体分子结构与先前研究的阴离子C <$N <$N三齿-Phbpy（HPhbpy = 6-（phenyl）-2，2 ′-bipyridine）配体的[Ni <$（C <$N <$N）<$X]配合物非常相似，但分子结构中的键长略有不同。这些N <$C <$N和C <$N <$N Ni配合物之间存在很大的差异，这可以追溯到X共配体对碳阴离子苯醚基团的不同取向，反式或顺式，以及不同的配体模式，Py-Ph-Py与Ph-Py-Py，被发现的紫外-可见吸收光谱和电化学还原，而氧化电位非常相似。扩展的DFT计算与TPSSh功能相关联的冷漠的氧化电位与保守能量的金属载HOMO。相比之下，N∧C∧N配体的π-受体质量的降低转化为LUMO的不稳定，大约。400 mV和蓝移的领先的可见光跃迁的80 nm，在非常好的协议与实验数据。
A series of cyclometalated Ni(II) complexes [Ni(PyPhPy)X] containing anionic N∧C∧N– tridentate ligand Py(Ph–)Py 2,6-di(2-pyridyl)benzene-1-ide, (Py(HPh)Py = 1,3-di(2-pyridyl)benzene) and X = Cl, Br, or I as coligands, were studied. All three complexes were obtained through direct C–H base-assisted nickelation from NiX2 and Py(HPh)Py using KOAc/K2CO3 in nonpolar high-boiling point solvents. While the overall molecular structures are quite similar to those of the previously studied [Ni(C∧N∧N)X] complexes with the anionic C∧N∧N tridentate –Phbpy (HPhbpy = 6-(phenyl)-2,2′-bipyridine) ligand, bond lengths in the molecular structures are slightly different. Large differences between these N∧C∧N and C∧N∧N Ni complexes which can be traced to the different orientation of the X coligand to the carbanionic phen-ide group, trans or cis, and the different ligand pattern, Py–Ph–Py versus Ph–Py–Py, were found for the UV–vis absorption spectra and the electrochemical reductions, while the oxidation potentials are very similar. Extended DFT calculations with the TPSSh functional associate the indifference of oxidation potentials with conserved energies of metal-borne HOMOs. By contrast, the diminished π-acceptor qualities of the N∧C∧N ligand translate into a destabilization of the LUMO by ca. 400 mV and a blue-shift of the leading visible transition by 80 nm in very good agreement with the experimental data.