Exploration of new routes to boranes and carboranes

TL;DRAbstract

The crystal chemistry of binary metal borides in the composition range M(_4) to MB(_12) and the hydrolytic chemistry of reactive metal borides to give boranes are reviewed. The thermal interconversion reactions of the smaller volatile boranes from B(_2)H(_6) to B(_10)H(_14) is critically examined and a rationalisation of their reactions with the transient Lewis acid species {BH(_3)), (B(_3)H(_7)) and (B(_4)H(_8)) is developed. This approach reveals a pattern of step-wise cage-growth for nido boranes which first seem to ligate a BH(_3) unit and then eliminate H(_2) giving the next higher homologue. Also, a structure-reactivity relationship for B(_2)H(_6) and the arachno boranes is suggested where the terminal hydrogens of the BH(_2) groups are thought to possess hydridic character which dominates their reactions with the Lewis acid intermediates. This work is partially extended to the cage-expansion and pyrolysis reactions of the anionic boron hydrides. A detailed review is presented of

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