Nekvinda Jan, Bavol Dmytro, Litecká Miroslava, Tüzün Ece Zeynep, Dušek Michal, Grüner Bohumír
Institute of Inorganic Chemistry of the Czech Academy of Sciences, Hlavní 1001, Husinec-Řež 25068, Czech Republic.
Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 8, 182 21, Czech Republic.
Dalton Trans. 2024 Mar 26;53(13):5816-5826. doi: 10.1039/d4dt00072b.
Carbon substituted cobalt bis(dicarbollide) alkyl halides [(1-X-(CH)-1,2-CBH)(1,2-CBH)-3,3'-Co]MeN (X = Br, I; = 1-3) are prepared in high yields (>90%) from their corresponding alcohols without side skeletal substitutions. These species offer access to the synthesis of aromatic cobalt bis(dicarbollide) amines, however only for particular terminal halogen substitution, the propylene pendant arm, and under appropriately controlled reaction conditions. Thus, the compounds substituted at cage carbon atoms with a propylene linker and terminal aromatic amine groups could be prepared. In other cases, numerous irregular reaction pathways occur, undoubtedly as a consequence of the bulky anionic boron cage in close proximity to the reaction site. Among them, an unusual intramolecular hydroboration forming rigidified carbon-to-boron bridged isomeric anions with an asymmetric structure that correspond to formulae [(1,8'-μ-CH)-(1,2-CBH)(1',2'-CBH)-3,3'-Co] and [(1,7'-μ-CH)-(1,2-CBH)(1',2'-CBH)-3,3'-Co] is described herein and the former isomer is structurally characterized. This product with a restrained geometry is widely accessible through nucleophile and/or thermally induced decomposition of (pseudo)halides attached to the cage an ethylene linker. Surprisingly enough, also doubly bridged isomeric species [(1,8-μ-CH-1,2-CBH)-3,3'-Co] and [(1,7-μ-CH-1,2-CBH)-3,3'-Co] are available in good yield using these methods. Furthermore, other more typical side reactions are discussed, nucleophilic reactions of propyl halides with MeN formed apparently by disproportionation of MeN at higher temperatures or with pyridine used as a base.
碳取代的钴双（二碳硼烷）卤代烷烃[(1-X-(CH)-1,2-C₂B₉H₁₀)(1,2-C₂B₉H₁₀)-3,3'-Co]MeN（X = Br、I；n = 1-3）由其相应的醇以高产率（>90%）制备而成，且无骨架侧链取代。这些化合物可用于合成芳基钴双（二碳硼烷）胺，但仅适用于特定的末端卤素取代、丙烯侧链以及在适当控制的反应条件下。因此，可以制备在笼碳原子上被丙烯连接基和末端芳基胺基团取代的化合物。在其他情况下，会出现许多不规则的反应途径，这无疑是由于庞大的阴离子硼笼靠近反应位点所致。其中，本文描述了一种不寻常的分子内硼氢化反应，形成具有刚性碳-硼桥连的异构阴离子，其结构不对称，对应于[(1,8'-μ-CH)-(1,2-C₂B₉H₁₀)(1',2'-C₂B₉H₁₀)-3,3'-Co]和[(1,7'-μ-CH)-(1,2-C₂B₉H₁₀)(1',2'-C₂B₉H₁₀)-3,3'-Co]的分子式，并且对前一种异构体进行了结构表征。这种几何结构受限的产物可通过亲核试剂和/或热诱导连接在笼上的（假）卤化物（乙烯连接基）分解广泛获得。令人惊讶的是，使用这些方法还能以良好的产率得到双桥连的异构物种[(1,8-μ-CH-1,2-C₂B₉H₁₀)-3,3'-Co]和[(1,7-μ-CH-1,2-C₂B₉H₁₀)-3,3'-Co]。此外，还讨论了其他更典型的副反应，即丙基卤化物与显然是由MeN在较高温度下歧化形成的MeN或用作碱的吡啶的亲核反应。
