▁heter o at oms . ▁ ▁Organ ob or on ▁chemical s ▁have ▁been ▁employed ▁in ▁uses ▁as ▁diverse ▁as ▁bor on ▁car b ide ▁( see ▁below ), ▁a ▁complex ▁very ▁hard ▁cer am ic ▁composed ▁of ▁bor on - car bon ▁cluster ▁an ions ▁and ▁c ations , ▁to ▁car bor anes , ▁carbon - bor on ▁cluster ▁chem istry ▁comp ounds ▁that ▁can ▁be ▁hal ogen ated ▁to ▁form ▁re active ▁structures ▁including ▁car bor ane ▁acid , ▁a ▁super ac id . ▁As ▁one ▁example , ▁car bor anes ▁form ▁useful ▁mole cular ▁mo iet ies ▁that ▁add ▁considerable ▁amounts ▁of ▁bor on ▁to ▁other ▁bio chem ical s ▁in ▁order ▁to ▁synth es ize ▁bor on - cont aining ▁comp ounds ▁for ▁bor on ▁neut ron ▁capture ▁ther apy ▁for ▁cancer . ▁ ▁Comp ounds ▁of ▁B ( I ) ▁and ▁B ( II ) ▁Although ▁these ▁are ▁not ▁found ▁on ▁Earth ▁naturally , ▁bor on ▁forms ▁a ▁variety ▁of ▁stable ▁comp ounds ▁with ▁formal ▁ox id ation ▁state ▁less ▁than ▁three . ▁As ▁for ▁many ▁c oval ent ▁comp ounds , ▁formal ▁ox id ation ▁states ▁are ▁often ▁of ▁little ▁meaning ▁in ▁bor on ▁hyd rides ▁and ▁metal ▁bor ides . ▁The ▁hal ides ▁also ▁form ▁derivatives ▁of ▁B ( I ) ▁and ▁B ( II ). ▁B F , ▁is oe lect ron ic ▁with ▁N 2 , ▁cannot ▁be ▁isolated ▁in ▁cond ensed ▁form , ▁but ▁B 2 F 4 ▁and ▁B 4 Cl 4