To explore the displacement of Zn2+ by Ni2+ from within N-, S-, and O-chelate ligands, (N-(3-thiabutyl)-N′-(3-thiapentaneoate)-1,4-diazacycloheptane)zinc(II), Zn-1′-Ac, and 1,4-diazacycloheptane-1,4-diylbis(3-thiapentanoato) zinc(II), Zn-1′-Ac2, were reacted with Ni(BF4)2 in a methanol solution and were found to yield, in both cases, the bright blue, hexa-coordinate Ni-1′-Ac2 metal-exchanged product. The latter conditions imply an intact-ligand unwrapping process as the hexadentate N2S2O2 ligand is transferred from zinc to nickel. The former involves transfer of the pentadentate N2S2O ligand generating a green, penta-coordinate nickel intermediate which engages in CH2CO2 fragment scavenging from a second zinc unit. This conclusion is supported by the observed analogous reformulation of the stable Zn-1′-Ac complex into Zn-1′-Ac2 and the dithiolato [Zn-1′]2 dimer. To our knowledge, this is a rare (possibly the first) example of cannibalism reported in such ligand systems. The M-1′-Ac2 complexes were characterized by X-ray diffraction and compared to the directly synthesized products.
为了探讨Zn2+被Ni2+从N、S和O螯合
配体中置换的过程,(N-(3-
硫丁基)-N'-(3-
硫戊酸)-1,4-二氮杂环七烷)
锌(II)(Zn-1′-Ac)和1,4-二氮杂环七烷-1,4-二基-双(3-
硫戊酸)
锌(II)(Zn-1′-Ac2)在
甲醇溶液中与Ni(
BF4)2反应,发现两者均产生亮蓝色的六配位Ni-1′-Ac2
金属交换产物。后者的条件表明,在该六齿N2S2O2
配体从
锌转移到
镍的过程中,
配体保持完好并发生解包过程。前者涉及五齿N2S2O
配体的转移,生成绿色的五配位
镍中间体,该中间体参与从第二个
锌单元中捕获CH2CO2片段。这一结论得到了观察到的稳定Zn-1′-Ac复合物重新构造为Zn-1′-Ac2和二
硫杂环[Zn-1′]2二聚体的支持。据我们所知,这是在这样的
配体体系中报告的稀有(可能是第一个)自相吞噬的例子。M-1′-Ac2复合物通过X射线衍射进行了表征,并与直接合成的产品进行了比较。