Research School of Chemistry, The Australian National University, Canberra, ACT 0200, Australia.
Dalton Trans. 2023 Feb 14;52(7):2164-2174. doi: 10.1039/d2dt03984b.
The pro-ligands 1,8-bis(di-R-phosphinomethyl)-2,3-dihydroperimidine (RHPm, R = phenyl, cyclohexyl) react with [RhCl(CE)(PPh)] (E = O, S) to afford the bimetallic complexes [RhCl(CE)(μ-RHPm)] (E = O, S). Upon heating, these species undergo double C-H activation to afford the N-heterocyclic carbene (NHC) pincer complexes [RhCl(RPm)]. Reduction of [RhCl(CO)(μ-PhHPm)] with KC results in the bimetallic rhodium(0) complex, [Rh(μ-CO)(PhHPm)], with a formal Rh-Rh bond and a hydrogen-bonding interaction between rhodium and the central methylene group (C-H⋯Rh = 2.802 Å). Upon treatment with tritylium, ferrocenium or triphenylcyclopropenium tetrafluoroborates this species undergoes double C-H activation to afford a mononuclear NHC pincer complex salt, [Rh(CO)(PhPm)]BF. Treatment of [RhCl(CO)(PhHPm)] with lithium (trimethylsilyl)acetylide provides another bimetallic species, [Rh(CCSiMe)(CO)(PhHPm)], however heating this species does not proceed cleanly to the monomeric NHC complex, [Rh(CCSiMe)(CO)(PhPm)] which may however be obtained from [RhCl(RPm)] and LiCCSiMe.
亲配体 1,8-双（二-R-膦甲基）-2,3-二氢过哌啶（RHPm，R = 苯基，环己基）与[RhCl（CE）（PPh）]（E = O，S）反应，得到双金属配合物[RhCl（CE）（μ-RHPm）]（E = O，S）。这些物种在加热时会经历双重 C-H 活化，生成 N-杂环卡宾（NHC）钳形配合物[RhCl（RPm）]。用 KC 还原[RhCl（CO）（μ-PhHPm）]得到双金属铑（0）配合物[Rh（μ-CO）（PhHPm）]，其中存在一个形式上的 Rh-Rh 键和一个铑与中心亚甲基之间的氢键（C-H···Rh = 2.802 Å）。该物种与三苯甲基、三氟甲磺酸铁或三苯基环丙烯四氟硼酸盐反应，会经历双重 C-H 活化，生成单核 NHC 钳形配合物盐[Rh（CO）（PhPm）]BF。[RhCl（CO）（PhHPm）]与锂（三甲基硅基）乙炔化物反应生成另一种双金属物种[Rh（C≡CSiMe）（CO）（PhHPm）]，但加热该物种不会干净地转化为单核 NHC 配合物[Rh（C≡CSiMe）（CO）（PhPm）]，但可以从[RhCl（RPm）]和 LiC≡CSiMe 获得。
