New intermediate-spin chloroiron(III) complex with a mixed nitrogen– sulfur co-ordination sphere ‡
作者:Marie-Aude Kopf、Daniel Varech、Jean-Pierre Tuchagues、Daniel Mansuy、Isabelle Artaud
DOI:10.1039/a706664c
日期:——
A new tetradentate proligand, 6,6â²-bis(2,2-diphenyl-2-sulfanylethyl)-2,2â²-bipyridine (H2L), involving two nitrogen bases and two thiols, has been synthesized. The crystal structure of its chloroiron(III) complex [FeL(Cl)] exhibits a five-co-ordinate iron in a distorted square-pyramidal structure including a long FeâCl axial bond. Its effective magnetic moment (µeff = 3.8 µB from 10 to 300 K) and its Mössbauer parameters [δ = 0.328(5) mm sâ1 and ÎEQ = 2.543(9) mm sâ1 at 293 K] are consistent with a pure intermediate S = spin state for the iron(III). This complex exhibits a sulfur-to-iron charge transfer absorption at 490 nm and a one-electron reduction wave at â415 mV (vs. SSCE). Upon reaction with tetrabutylammonium hydroxide it is converted into the µ-oxo complex [Fe2L2O], which has been characterized by mass spectral and elemental analyses. Its formation is reversible in dmf upon addition of trifluoroacetic acid in the presence of chloride anion, as shown by 1H NMR and UV/VIS spectroscopy and electrochemistry. The [FeL(Cl)] complex appears to be the first example of an iron(III) complex with a mixed nitrogenâsulfur co-ordination sphere in a pure S = ground spin state.
合成了一种新的四齿配体,6,6-双(2,2-二苯基-2-硫烷基乙基)-2,2-联吡啶(H2L),涉及两个氮碱基和两个硫醇。其氯铁(III)络合物[FeL(Cl)]的晶体结构呈现出扭曲的方锥体结构中的五配位铁,包括长的Fe-Cl轴键。其有效磁矩(μeff = 3.8 µB,从 10 到 300 K)及其穆斯堡尔参数 [δ = 0.328(5) mm s–1 和 ÎEQ = 2.543(9) mm s– 1 at 293 K] 与铁 (III) 的纯中间体 S = 自旋态一致。该配合物在 490 nm 处表现出硫到铁的电荷转移吸收,并在 415 mV 处表现出单电子还原波(相对于 SSCE)。与氢氧化四丁基铵反应后,它转化为 µ-氧配合物 [Fe2L2O],并通过质谱和元素分析对其进行了表征。如 1H NMR、UV/VIS 光谱和电化学所示,在氯阴离子存在下添加三氟乙酸后,其形成在 dmf 中是可逆的。 [FeL(Cl)]络合物似乎是铁(III)络合物的第一个例子,其具有纯S=基自旋态的混合氮硫配位球。