Two configurationally isomeric ligands, namely, 2-((E)-benzylideneamino)-3-((pyridin-2-ylmethyl)amino)maleonitrile (HL1) and 2-(benzylamino)-3-((E)-(pyridin-2-ylmethylene)amino)maleonitrile (HL2), were synthesized and fully characterized, which are malenonitrile-tethered, N atom donors tridentate ligands. Structurally, they differ in the interchangeable position of amine and imine group only. Under the same reaction condition, Ni(II) invoked the transformation of (L1)- to (L2)- via simultaneous oxidation of amine to imine and the reduction of imine to amine. Two sequential 1,5-proton transfer pathways were anticipated for this type of unusual amine-imine oxidation/reduction process under acidic medium. In contrast, Co(II) was silent to such amine-imine interconversion reactions under both HL1 and HL2 ligand environment. The variation in electronic requirement might differentiate between both ligands such that HL2 influenced the arial oxidation of Co(II) to Co(III) but HL1 could not. The redox chemistry of Co(II)/Co(III) complexes with either HL1 or HL2 was explained using cyclic voltammetry and UV-vis spectroscopy.

中文翻译：

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共轭胺-亚胺-亚胺配体中金属离子（NiII与CoII）介导的异常胺-胺互变：合成，结构和表征。

两个构型异构的配体，即2-（（E）-亚苄基氨基）-3-（（吡啶-2-基甲基）氨基）马腈（HL1）和2-（苄基氨基）-3-（（E）-（吡啶-合成并完全表征了2-基亚甲基）氨基）马腈（HL2），它们是由马来腈连接的N原子供体的三齿配体。在结构上，它们仅在胺和亚胺基的互换位置上不同。在相同的反应条件下，Ni（II）通过将胺同时氧化为亚胺并将亚胺还原为胺来引发（L1）-向（L2）-的转化。对于这种在酸性介质下的异常胺-亚胺氧化/还原过程，预计会有两个连续的1,5-质子转移途径。相反，在HL1和HL2配体环境下，Co（II）对这种胺-亚胺的相互转化反应沉默。电子需求的变化可能会区分两个配体，使得HL2影响了Co（II）转化为Co（III）的区域氧化，而HL1则没有。使用循环伏安法和紫外可见光谱法解释了Co（II）/ Co（III）与HL1或HL2的配合物的氧化还原化学。