0 ▁and ▁ 1 5 0 0 – 2 0 0 0 ▁t onnes / year ▁respectively . ▁ ▁Most ▁iron ▁pent ac ar b ony l ▁produced ▁is ▁decom posed ▁on ▁site ▁to ▁give ▁pure ▁car b ony l ▁iron ▁in ▁anal ogy ▁to ▁car b ony l ▁nick el . ▁Some ▁iron ▁pent ac ar b ony l ▁is ▁burn ed ▁to ▁give ▁pure ▁iron ▁ox ide . ▁Other ▁uses ▁of ▁pent ac ar b ony l ir on ▁are ▁small ▁in ▁comparison . ▁ ▁Re actions ▁ ▁Dec ar b ony lation ▁Pur ified ▁iron ▁pent ac ar b ony l ▁can ▁be ▁decom posed ▁to ▁produce ▁car b ony l ▁iron , ▁a ▁high - p urity ▁prepar ation ▁of ▁iron ▁metal . ▁ ▁CO ▁substitution ▁re actions ▁Many ▁comp ounds ▁are ▁derived ▁from ▁Fe ( CO ) 5 ▁by ▁substitution ▁of ▁CO ▁by ▁Lewis ▁bases , ▁L , ▁to ▁give ▁derivatives ▁Fe ( CO ) 5 − x L x . ▁ ▁Common ▁Lewis ▁bases ▁include ▁is oc yan ides , ▁ ▁t ert i ary ▁ph osph ines ▁and ▁ar s ines , ▁and ▁al ken es . ▁ ▁Usually ▁these ▁lig ands ▁dis place ▁only ▁one ▁or ▁two ▁CO ▁lig ands , ▁but ▁certain ▁accept or ▁lig ands ▁such ▁as ▁P F 3 ▁and ▁is oc yan ides ▁can ▁proceed ▁to ▁t etra - ▁and ▁pent as ub st itution . ▁ ▁These ▁re actions ▁are ▁often ▁induced ▁with ▁a ▁catal yst ▁or ▁light . ▁