Novel multidentate ligand composed of phosphorus-bridged ferrocene units

磷桥二茂铁齐聚物具有一种特殊的分子结构，它源于一个具有圆柱形状的二茂铁部分。低聚物可以通过与金属片段、主族元素和/或有机连接基的键进一步组装。在这个项目中，选择环状二聚体作为合成目标，以阐明其作为配体的功能。合成了两个P原子与两个1，1 ′-二茂铁二亚基双键相连的P（NEt_2）-桥联[1.1]二茂铁烷。顺式和反式P（NEt_2）-桥连[1.1]二茂铁烷的混合物用HCl氯化，伴随着容易的反式-顺式转化，选择性地得到PC 1-桥连[1.1]二茂铁烷的顺式异构体，由此得到的氯膦用PhLi，Me_3SiCH_2Li，p-TolMgBr或HNEt_2处理，得到相应的二芳基化，二烷基化，或保留顺式构象的二胺化合物。相对稳定性。在甲苯中加热时，PPh-桥连的[1.1]二茂铁烷的一种和异构体几乎可以完全转化为一种顺式异构体，这表明和异构体相对于顺式异构体的热不稳定性。上述空间要求高和供电子的二膦螯合物适用于动力学和/或化学稳定不饱和络合物。在磷桥上带有Ph或Me_3SiCH_2基团的四面体钴（II）二氯配合物的烷基化反应成功地得到了相应的二烷基配合物，而CoCl_2（dppp）的类似烷基化反应则得到了Co^0（dppp）_2。所得到的二烷基配合物是第一个配位不饱和钴（II）（二膦）（二烷基）配合物的分离和X-射线分析，其特征在于。该配合物有望作为钴（II）催化的Heck型反应的模型中间体。

Phosphorus-bridged ferrocene oligomers possess a peculiar molecular structure which stems from a ferrocene moiety bearing a cylindrical shape. The oligomers can be further assembled via bonds with metal fragments, main group elements, and/or organic linkers. In this project, cyclic dimers are chosen as synthetic targets in order to elucidate their functionality as a ligand.Preparation. P(NEt_2)-bridged [1.1]ferrocenophane, in which two P atoms are linked doubly with two 1,1'-ferrocenediy1 moieties, were prepared. Chlorination with HC1 of a mixture of syn-and anti-P(NEt_2)-bridged [1.1]ferrocenophane accompanied facile anti-to-syn conversion to give the syn isomer of PC1-bridged [1.1]ferrocenophane selectively, and treatment of the chlorophospine thus obtained with PhLi, Me_3SiCH_2Li, p-TolMgBr, or HNEt_2 afforded the corresponding diarylated, dialkylated, or diaminated compounds with the syn conformation retained.Relative Stability. An and isomer of PPh-bridged [1.1]ferrocenophane could be converted almost completely to a syn isomer upon heating in toluene, indicative of the thermal instability of the and isomer over the syn isomer.Utility. Sterically demanding and electron-donating diphosphine chelates described above are suitable for kinetically and/or thermodynamically stabilizing an unsaturated complex. Alkylation of a tetrahedral cobalt(II)dichloro complex bearing a Ph or Me_3SiCH_2 group on the phosphorus bridge gave a corresponding dialkyl-complex successfully, whereas similar alkylation of CoCl_2(dppp) resulted in a formation of Co^0(dppp)_2. The dialkyl complex obtained is the first coordinatively-unsaturated cobalt(II)(diphosphine)(dialkyl) complex isolated and characterized by X-ray analysis. This complex is expected to serve as a model intermediate in the cobalt(II)-catalyzed Heck-type reactions.