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:
 * H2Fe(CO)4 +  KOH  →  K[HFe(CO)4]  +  H2O

Potassium tetracarbonyliron hydride is prepared by treating iron pentacarbonyl with potassium hydroxide:
 * Fe(CO)5 +  2 KOH  →  K[HFe(CO)4]  +  KHCO3

Potassium tetracarbonyliron hydride is an intermediate in the synthesis of trisubstituted phosphine complexes:
 * K[HFe(CO)4] +  3 PBu3  +  EtOH  →  Fe(CO)2(PBu3)3  +  EtOK  +  2 CO  +  H2