Strucural Conversion of Sulfur-Bridged Polynuclear Complexes by Metal Replacement Reaction

在金属离子的辅助下，八金属配合物与两个或三个硫酸盐配体的聚集形成了多种含有多个手性中心的s桥多核配合物。这些多核配合物的结构高度依赖于与八面体配合物结合的金属离子的配位几何。为了更好地了解这种类型的s桥结构的性质特征，有必要研究由（三）或（二）硫代络合物单元组成的类似的s桥多核配合物。在本研究中，我们发现了一种新型的S桥式Co^<III>Ag^I_3Co^<III>五核配合物[Ag_3{Co(aet) _3}_2] ^<3+>和[Ag_3{Co(L-cys-N，S) _3] ^<0or3->与线性Ag^+反应制备了[Ag_3{Co(L-cys-N，S) _3] ^<3->。在Co^<III>Ag^I_3Co^<III>结构中，来自两个面(S)-[Co(aet或L-cys-N，S) _3] ^<0or3->单元的两个硫代S原子分别与三个Ag原子对应，使得三个S-Ag-S键形成了三螺旋结构。另一方面，S桥接的Co^<III>Ni^<II>Co^<III>三核配合物[Ni{Co(aet) _2 (en)}_2]Cl_4与Na_2 [PdCI_4]的反应比例为1：1得到s桥接Co^<III>Pd^<II>Co^<III>三核配合物[Pd{Co(aet) _2 (en)}_2]Cl_4，对应的1:2反应得到s桥接Co^<III>Pd^<II>双核配合物[PdCl_2{Co(aet) _2 (en)}]CI。在Co^<III>Pd^<II>Co^<III>结构中，Pd^<II>原子由来自两个顺式(S)-[Co(aet) _2 (en)] ^+的4个S原子配位，而在Co_<III>Pd_<II>结构中，Pd_<II>原子除了来自一个八面体单元的2个S原子外，还由两个Cl原子配位。

The aggregation of octaetal complexes with two or three thiolate ligands assisted by metal ions has been shown to form a variety of S-bridged polynuclear complexes containing several chiral centers. It has been noted that the structures of these polynuclear complexes are highly dependent on the coordination geometry of metal ions incorporated with the octahedral complexes. In order to better understand the properties characteristic of the S-bridged structure of this type, it is necessary to investigate analogous S-bridged polynuclear complexes composed of (tris)- or (bis)thiolato complex-units.In this study, we have found that the novel S-bridged Co^<III>Ag^I_3Co^<III> pentanuclear complexes, [Ag_3{Co(aet) _3}_2] ^<3+> and [Ag_3{Co(L-cys-N,S) _3}_2, ] ^<3->, were prepared by reacting fac(S)-[Co(aet or L-cys-N,S) _3] ^<0or3-> with linear Ag^+. In the Co^<III>Ag^I_3Co^<III>structure, the two thiolato S atoms from two fac(S)-[Co(aet or L-cys-N,S) _3] ^<0or3-> units coordinate to each of three Ag atoms, such that the three S-Ag-S linkages form a triple helical structure, On the other hand, the reaction of an S-bridged Co^<III>Ni^<II>Co^<III> trinuclear complex, [Ni{Co(aet) _2 (en)}_2]Cl_4, with Na_2 [PdCI_4 ] in a ratio of 1 : 1 gave an S-bridged Co^<III>Pd^<II>Co^<III> trinuclear complex, [Pd{Co(aet) _2 (en)}_2]Cl_4, while the corresponding 1 : 2 reaction produced an S-bridged Co^<III>Pd^<II> dinuclear complex, [PdCl_2{Co(aet) _2 (en)}]CI.In the Co^<III>Pd^<II>Co^<III> structure the Pd^<II> atom is coordinated by four S atoms from two cis(S)-[Co(aet) _2 (en)] ^+ units, while the Pd_<II> atom in the Co_<III>Pd_<II> structure is coordinated by two Cl atoms besides two S atoms from one octahedral unit.