Functional Elemento-Organic Chemistry Unit, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
J Am Chem Soc. 2011 Jul 27;133(29):11058-61. doi: 10.1021/ja203333j. Epub 2011 Jul 5.
Diborane(6) as a H-bridged dimer of monoborane can be converted cleanly by two-electron reduction into diborane(6) dianion, which is isoelectronic with ethane, through B-B σ-bond formation when each boron atom has a bulky ligand on it. The existence of the B-B σ bond is supported by the X-ray molecular structure [B-B bond length of 1.924(3) Å], NMR studies, magnetic susceptibility measurements, and DFT calculations. Stepwise hydride abstraction reactions of the diborane(6) dianion produce the corresponding H-bridged diborane(5) anion and doubly H-bridged diborane(4) without B-B bond scission.
二硼烷(6)作为单硼烷的 H 桥二聚体，可以通过双电子还原，在每个硼原子上都有一个大体积配体时，通过 B-B σ 键的形成，干净地转化为与乙烷等电子的二硼烷(6)二负离子。X 射线分子结构 [B-B 键长为 1.924(3) Å]、NMR 研究、磁化率测量和 DFT 计算都支持 B-B σ 键的存在。二硼烷(6)二负离子的逐步氢化物抽离反应产生相应的 H 桥联二硼烷(5)阴离子和双 H 桥联二硼烷(4)，而不会发生 B-B 键断裂。
