Diborane dianions

This works well for all nido- and arachno-boranes but not for the c/o o-dianions, which are much less reactive. Reactions of B2H6 with NH3 are complex and, depending on the conditions, yield aminodiborane, H2B(/r-H)(/r-NH2)BH2, or the diammoniate of diborane, [BH2(NH3)2]-[BH4] (p. 165) at higher temperatures the benzene analogue borazine, (HNBH)3, results (see p. 210). 

Salts of this dianion can also be prepared via the pyrolysis of Et4N BH and the treatment of Et3NBH3 with diborane at 170°C. 

More recently, some carboranyl diborane(4) derivatives have been prepared from the reaction between 1, l,2-(HE)2C2B10Hio (E = S, Se) (generated in situ from Li2C2Bi0H10 followed by addition of elemental S or Se and acidification) and HC1. Two crystallographically characterised examples are the dianionic species 10 and 11, the latter representing the first example of a diborane(4) compound with B Se bonds. 

Moezzi A, Olmstead MM, Power PP (1992) Boron-boron double bonding in the species [B2R4] synthesis and structure of [ (Et20)Li 2 Mes2BB(Mes)Ph ], a diborane(4) dianion analog of a substituted ethylene. J Am Chem Soc 114 2715-2717... 

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