Effective Coordination Control by Utilizing the Cavity of Calixarenes

杯芳烃是一种多功能配体，不仅具有两种不同类型的配位位点，酚氧和芳烃环，而且还具有包涵位点（腔）。然而，杯芳烃腔内过渡金属配合物的配位化学仍有待探索。在这项研究中，我们研究了两个系列的杯[4]芳烃配合物，其中金属中心位于杯[4]芳烃的腔内。在Et_3N存在下，杯状[4]芳烃与[CpRu(CH_3CN)_3]PF_6反应，得到了钌-芳烃型配合物[CpRu{杯状[4]-(0)(OH)_3}](1)，产率较高。配合物1的x射线衍射研究表明，CpRu+片段存在于杯形[4]芳烃配体的腔中，并且1的Cp质子在1H NMR中表现出特有的高场位移。这一事实与Cp*Ru+片段与杯状[4]芳烃的络合形成鲜明对比，其中金属中心被束缚在ph…的外表面。更多的烯醛环（配合物2），和1可以被视为“自包合”产物。在配合物1中进一步引入一个Cp*Ru+片段，形成[(CpRu)(Cp*Ru){calix[4]-(0)(OH)_3}]+(3)的内外异构体，而在配合物2中引入一个CpRu+片段，形成其内外异构体。这些结果表明，CpRu+片段首先在杯芳烃分子的外表面得到配位，然后杯芳烃骨架的环反转得到内部配位产物。另一方面，用多种阳离子过渡金属配合物ML+处理[Ph_4P][ReO_2{p-tBu-calix[4]-(0)_4}](4)时，苯氧桥接Re-M配合物[ReO_2{p-tBu-calix[4]-(0)_4}ML] (5a, ML = Cu(NCMe)；5 b, Ag (Me2C0);5度,非盟(Ppha);5d, Rh(cod))产率高。配合物5a的异双核核位于腔内，显示出独特的光谱和化学行为。例如，配合物5a经过选择性的炔烃掺入，而配合物5d经过溶剂依赖的异构化形成π-芳烃型区域异构体。少

Calixarenes are known to serve as a versatile ligand not only with two distinct types of coordination sites, phenolic oxygens and arene rings, but also with an inclusion site (cavity). However, coordination chemistry of transition-metal complexes inside the cavity of calixarenes still remains to be explored. In this study we have investigated two series of calix[4]arene complexes in which the metal centers are located inside the cavity of calix[4]arenes.The reaction of calix[4]arene with [CpRu(CH_3CN)_3]PF_6 in the presence of Et_3N has been found to give the ruthenium-arene type complex [CpRu{calix[4]-(0)(OH)_3}] (1)in good yield. An X-ray diffraction study of complex 1 has revealed that the CpRu+ fragment resides in the cavity of the calix[4]arene ligand, and the Cp protons of 1 exhibit characteristic high-field shift in the ^1H NMR. This fact makes a sharp contrast to the complexation of a Cp*Ru+ fragment with calix[4]arene where the metal center is bound at the outside face of a ph … More enolic ring(complex 2), and 1 can be viewed as a "self-inclusion" product. Further introduction of a Cp*Ru+ fragment into complex 1 gives rise to the inside-outside isomer of [(CpRu)(Cp*Ru){calix[4]-(0)(OH)_3}]+ (3), while introduction of a CpRu+ into 2 leads to its outside-outside isomer. These results indicates that the CpRu+ moiety is first coordinates at the outside face of a calixarene molecule, and then the ring inversion of the calixarene skeleton affords the inside coordination product.On the other hand, when [Ph_4P][ReO_2{p-tBu-calix[4]-(0)_4}] (4)is treated with a variety of cationic transition metal complex ML+, the phenoxo-bridged Re-M complexes [ReO_2{p-tBu-calix[4]-(0)_4}ML] (5a, ML = Cu(NCMe); 5b, Ag(Me2C0); 5c, Au(Ppha); 5d, Rh(cod)) can be obtained in good yield. The heterodinuclear core of complex 5a is located inside the cavity and have revealed to show unique spectral and chemical behaviors. For example, complex 5a undergoes selective alkyne incorporation, while complex 5d undergoes solvent-dependent isomerization to π-arene type regioisomers. Less