Potassium tetracarbonyliron hydride
# Potassium tetracarbonyliron hydride

Potassium tetracarbonyliron hydride is the inorganic salt with the formula $K[HFe(CO)_4].$ A pale yellow solid, it is the potassium salt of $[HFe(CO)_4]^−,$ which is the conjugate base of iron tetracarbonyl dihydride:

    $H_2Fe(CO)_4$ + KOH → $K[HFe(CO)_4]$ + $H_2O$

Potassium tetracarbonyliron hydride is prepared by treating iron pentacarbonyl with potassium hydroxide:

    $Fe(CO)_5$ + 2 KOH → $K[HFe(CO)_4]$ + $KHCO_3$

Potassium tetracarbonyliron hydride is an intermediate in the synthesis of trisubstituted phosphine complexes:

    $K[HFe(CO)_4]$ + 3 $PBu_3$ + EtOH → $Fe(CO)_2(PBu_3)_3$ + EtOK + 2 CO + $H_2$
