In the pursuit of a “rotated” structure, and exploration of the influence of the aza nitrogen lone pair, the FeIFeI model complexes wherein two Fe(CO)3−xPx moieties are significantly twisted from the ideal configuration (torsion angle >30°) are reported. [Fe2(μ-S(CH2)2NiPr(X)(CH2)2S)(CO)4(κ2-dppe)]22+ (X = H, 4; Me, 5) prepared from protonation and methylation, respectively, of [Fe2(μ-S(CH2)2NiPr(CH2)2S)(CO)4(κ2-dppe)]2, 1, possess Φ angles of 34.1 and 35.4° (av.), respectively. Such dramatic twist is attributed to asymmetric substitution within the Fe2 unit in which a dppe ligand is coordinated to one Fe site in the κ2-mode. In the presence of the N⋯C(COap) interaction, the torsion angle is decreased to 10.8°, suggesting availability of lone pairs of the aza nitrogen sites within 1 is in control of the twist. Backbones of the bridging diphosphine ligands also affect distortion. For a shorter ligand, the more compact structure of [Fe2(μ-S(CH2)2NiPr(CH2)2S)(μ-dppm)(CO)4]2, 7, is formed. Dppm in a bridging manner allows achievement of the nearly eclipsed configuration. In contrast, dppe in [Fe2(μ-S(CH2)2NiPr(CH2)2S)(μ-dppe)(CO)4]2, 6, could twist the Fe(CO)3−xLx fragment to adopt the least strained structure. In addition, the N⋯C(COap) interaction would direct the twist towards a specific direction for the closer contact. In return, the shorter N⋯C(COap) distance of 3.721(7) Å and larger Φ angle of 26.5° are obtained in 6. For comparison, 3.987(7) Å and 3.9° of the corresponding parameters are observed in 7. Conversion of (μ-dppe)[Fe2(μ-S(CH2)2NiPr(CH2)2S)(CO)5]2, 2, to complex 1via an associative mechanism is studied.
为了追求 "旋转 "结构,并探索氮杂氮孤配对的影响,报告了 FeIFeI 模型复合物,其中两个 Fe(CO)3-x
Px 分子与理想构型(扭转角大于 30°)有明显的扭转。由[Fe2(μ-S(
CH2)2NiPr(X)( )2S)(CO)4(κ2-dppe)]2, 1 的质子化和甲基化分别制备的[Fe2(μ-S( )2NiPr( )2S)(CO)4(κ2-dppe)]22+(X = H, 4; Me, 5)的Φ角分别为 34.1 和 35.4°(平均值)。这种剧烈的扭转归因于 Fe2 单元内的不对称取代,其中 dppe
配体以 κ2 模式配位到一个 Fe 位点。在 N⋯C(COap)相互作用的情况下,扭转角减小到 10.8°,这表明 1 内氮杂位点的孤对作用控制了扭转。桥接二
膦配体的骨架也会影响扭曲。如果
配体较短,就会形成结构更紧凑的[Fe2(μ-S( )2NiPr( )2S)(μ-dppm)(CO)4]2,即 7。以桥接方式形成的 Dppm 可以实现近乎椭圆的构型。与此相反,[Fe2(μ-S( )2NiPr( )2S)(μ-dppe)(CO)4]2, 6 中的 dppe 可以扭曲 Fe(CO)3-xLx 片段,从而采用应变最小的结构。此外,N⋯C(COap) 相互作用会将扭曲引向一个特定的方向,以实现更紧密的接触。因此,6 中的 N⋯C(COap)距离较短,为 3.721(7) Å,Φ 角较大,为 26.5°。相比之下,7 中的相应参数为 3.987(7) Å 和 3.9°。研究了 (μ-dppe)[Fe2(μ-S( )2NiPr( )2S)(CO)5]2 通过缔合机理转化为复合物 1 的过程。