Assigning Hapticity to Cyclopentadienyl Derivatives of Antimony and Bismuth

The chelating diamide [Me2Si­{NAr}2]2– (Ar = 2,6-i-Pr2C6H3) has been used as an ancillary ligand in antimony and bismuth chemistry. In contrast to the monomeric antimony chloride compound Sb­(Me2Si­{NAr}2)Cl (1a), the bismuth derivative (1b) exists as a trimer in the solid state, linked by Bi···(arene) π-bonding and Bi···Cl interactions. Compounds 1a,b are used as an entry point into rare antimony and bismuth compounds incorporating Cp and Cp* ligands. Reactions of the chlorides with LiCp and KCp* afford the organometallic species E­(Me2Si­{NAr}2)­(C5R5) (2a, R = H, E = Sb; 2b, R = H, E = Bi; 3a, R = Me, E = Sb; 3b, R = Me, E = Bi). Variable-temperature NMR experiments indicate different fluxional processes occur in solution involving facile haptotropic shifts of the [C5R5]− ring. Structural characterization of 2b and 3a,b reveals monomeric compounds in which the cyclopentadienyl-derived ligand adopts a low hapticity in the solid state.螯合二酰胺[Me₂Si{NAr}₂]²⁻（其中Ar=2,6-二异丙基苯基，即2,6-i-Pr₂C₆H₃）已被用作锑化学与铋化学中的辅助配体。与单分子氯化锑化合物Sb(Me₂Si{NAr}₂)Cl（1a）不同，其铋衍生物（1b）在固态下以三聚体形式存在，通过Bi···(芳烃)π键相互作用与Bi···Cl相互作用实现连接。化合物1a和1b可作为制备含环戊二烯基（Cyclopentadienyl，Cp）与五甲基环戊二烯基（Pentamethylcyclopentadienyl，Cp*）配体的稀有锑、铋化合物的合成起始底物。该氯化物分别与环戊二烯基锂（LiCp）及五甲基环戊二烯基钾（KCp*）发生反应，得到有机金属物种E(Me₂Si{NAr}₂)(C₅R₅)（其中2a：R=H，E=Sb；2b：R=H，E=Bi；3a：R=Me，E=Sb；3b：R=Me，E=Bi）。变温核磁共振（NMR）实验表明，溶液中存在不同的动态流变过程，涉及[C₅R₅]⁻环的快速η配位数迁移。对化合物2b、3a和3b的结构表征结果显示，其均为单分子化合物，且固态下环戊二烯基衍生配体呈现低配位点数（低η值）的配位模式。