Monocarbaborane anion chemistry. {COOH}, {CH2OH} and {CHO} units as functional groups on ten-vertex monocarbaborane anionic compounds

B10H14 reacts with para-C6H4(CHO)(COOH) in aqueous KOH solution to give the [nido-6-CB9H11-6-(C6H4-para-COOH)](-) anion 1, which undergoes cage closure with iodine in alkaline solution to give the [closo-2-CB9H9-2-(C6H4-para-COOH)](-) anion 2. Upon heating, anion 2 rearranges to form the [closo-1-CB9H9-1-(C6H4-para-COOH)](-) anion 3. Similarly, B10H14 with glyoxylic acid OHCCOOH in aqueous KOH gives the [arachno-6-CB9H13-6-(COOH)](-) anion 4, which undergoes cage closure with iodine in alkaline solution to give the [closo-2-CB9H9-2-(COOH)](-) anion 5. Upon heating, anion 5 rearranges to give the [closo-1-CB9H9-1-(COOH)](-) anion 6. Reduction of the {COOH} anions 3 and 6 with diisobutylaluminium hydride gives the {CH2OH} hydroxy anions [closo-1-CB9H9-1-(C6H4-para-CH2OH)](-) 7 and [closo-1-CB9H9-1-(CH2OH)](-) 8 respectively. The [closo-1-CB9H9-1-(C6H4-para-CH2OH)](-) anion 7 can also be made via isomerisation of the [closo-2-CB9H9-2-(C6H4-para-CH2OH)](-) anion 9, in turn obtained from the [nido-6-CB9H11-6-(C6H4-para-CH2OH)](-) anion 10, which is obtained from the reaction of B10H14 with terephthaldicarboxaldehyde, C6H4-para-(CHO)(2), in aqueous KOH solution. Oxidation of the hydroxy anions 7 and 8 with pyridinium dichromate gives the aldehydic [closo-1-CB9H9-1-(C6H4-para-CHO)](-) anion 11 and the aldehydic [closo-1-CB9H9-1-(CHO)](-) anion 12 respectively, characterised as their 2,4-dinitrophenylhydrazone derivatives, the [closo-1-CB9H9-1-C6H4-para-CH=N-NHC6H3(NO2)(2)](-) anion 13 and the [closo-1-CB9H9-1-CH=N-NHC6H3(NO2)(2)](-) anion 14 respectively.