The new pyridazine containing iron complexes, [N,N,N′,N′‐tetrakis(3‐pyridazylmethyl)propylenediamine]iron(II)(PF₆)₂ (1) and [N,N′‐bis(2‐pyridazylmethyl)‐N,N′‐bis(2‐pyridylmethyl)propylenediamine]iron(II) (PF₆)₂ (2) were synthesized and their reactivity towards protonation was compared to that of the analogous tetrapyridine complex [N,N,N′,N′‐tetrakis(2‐pyridylmethyl)propylenediamine]iron(II)(PF₆)₂ (3). The solution and solid‐state structures were confirmed by NMR and X‐ray crystallographic studies. For 1–3, the ligands bind in a hexadentate fashion giving similar octahedral structures with an N₆ coordination environment. Across the series, the increasing number of pyridazines has only modest effects on the spectroscopic and electrochemical properties of the metal. Nevertheless, their reactivity towards protonation is drastically different. While 2 and 3 decompose in the presence of strong acids, 1 is able to be stably protonated as a result of cooperative second sphere interactions.

中文翻译：

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哒嗪/吡啶类含氮杂杂环铁（II）配合物的第二配位域中的协同相互作用有利于质子化

新型哒嗪铁配合物，[ N，N，N'，N'-四（3-吡啶并甲基甲基）丙二胺]铁（II）（PF ₆）₂（1）和[ N，N'-双（2-吡啶并甲基） ）-N，N'-双（2-吡啶基甲基）丙二胺]铁（II）（PF ₆）₂（2）的合成，并将其对质子的反应性与类似的四吡啶配合物[ N，N，N'，N'-四（2-吡啶基甲基）丙二胺]铁（II）（PF ₆）₂（3）。溶液和固态结构已通过NMR和X射线晶体学研究证实。为1 - 3，配体结合在一六齿的方式给予类似八面体结构具有N ₆配位环境。在整个系列中，越来越多的哒嗪仅对金属的光谱和电化学性质产生适度的影响。然而，它们对质子化的反应性截然不同。当2和3在强酸存在下分解时，1 由于第二球体的相互作用，它能够稳定地质子化。