The synthesis and characterization of four new Ni(II) bis(NHC) bipy complexes (bipy = 4, 4′-bipyridine, NHC = N-heterocyclic carbene) are reported. These represent the first examples of the Ni^II(NHC₂) L₂ class of compounds, where L is a two-electron-donor ligand. The introduction of a double propyl bridged bis-NHC ligand (C^Prop2C) imparts reversibility to the electrochemistry of these complexes. The electrochemical response includes two reductions, the first believed to be bipy ligand based, bipy^0/–, and the second metal based. The unusual ligand arrangements in these complexes result in electronic structures in which both the HOMOs and LUMOs are ligand-based, as determined by DFT analysis of all four compounds.

中文翻译：

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带有双（N-杂环卡宾）配体的多官能Ni（II）联吡啶配合物的合成与表征

报道了四种新的Ni（II）bis（NHC）bipy配合物（bipy = 4，4'-联吡啶，NHC = N-杂环卡宾）的合成和表征。这些代表了Ni ^II（NHC ₂）L ₂类化合物的第一个实例，其中L是双电子给体配体。双丙基桥接双-NHC配体（C ^Prop2 C）的^引入赋予了这些配合物的电化学可逆性。电化学响应包括两个还原，第一个被认为是基于联配体的配体，联配^{0 /-}，以及第二种金属。这些复合物中异常的配体排列导致电子结构，其中HOMO和LUMO都是基于配体的，这是通过对所有四种化合物进行DFT分析确定的。