( CO ) 5 ▁is ▁produced ▁by ▁the ▁reaction ▁of ▁fine ▁iron ▁particles ▁with ▁carbon ▁mon ox ide . ▁ ▁The ▁comp ound ▁was ▁described ▁in ▁a ▁journal ▁by ▁Mond ▁and ▁L anger ▁in ▁ 1 8 9 1 ▁as ▁" a ▁somewhat ▁vis c ous ▁liquid ▁of ▁a ▁pale - yellow ▁colour ." ▁ ▁Sam ples ▁were ▁prepared ▁by ▁treatment ▁of ▁fin ely ▁divided , ▁ox ide - free ▁iron ▁pow der ▁with ▁carbon ▁mon ox ide ▁at ▁room ▁temperature . ▁ ▁Indust rial ▁synth esis ▁of ▁the ▁comp ound ▁requires ▁relatively ▁high ▁temper atures ▁and ▁press ures ▁( e . g . ▁ 1 7 5 ▁at m ▁at ▁ 1 5 0   ° C ) ▁as ▁well ▁as ▁special , ▁chem ically ▁resist ant ▁equipment ▁( e . g . ▁composed ▁of ▁co pper - sil ver ▁allo ys ). ▁Pre par ation ▁of ▁the ▁comp ound ▁at ▁the ▁labor atory ▁scale ▁avoid s ▁these ▁comp lications ▁by ▁using ▁an ▁i od ide ▁intermediate : ▁▁ ▁Fe I 2 ▁+ ▁ 4   CO ▁→ ▁Fe ( CO ) 4 I 2 ▁▁ 5   Fe ( CO ) 4 I 2 ▁+ ▁ 1 0   C u ▁→ ▁ 1 0   C u I ▁+ ▁ 4   Fe ( CO ) 5 ▁+ ▁Fe ▁ ▁Fe ( CO ) 5 ▁is ▁sensitive ▁to ▁light . ▁Phot od is soci ation ▁of ▁Fe ( CO ) 5 ▁produces ▁Fe 2 ( CO ) 9 , ▁a