 As demonstrated later, the compound was not a metal carbonyl, but the potassium salt of ´hexahydroxy benzene and the potassium salt of dihydroxy acetylene

The synthesis of the first true heteroleptic metal carbonyl complex was performed by Paul Schützenberger in 1868 by passing chlorine and carbon monoxide over platinum black, where dicarbonyldichloroplatinum (Pt(CO)2Cl2) was formed.Ludwig Mond, one of the founders of Imperial Chemical Industries, investigated in the 1890s with Carl Langer and Friedrich Quincke various processes for the recovery of chlorine which was lost in the Solvay process by nickel metals, oxides, and salts.As part of their experiments the group treated nickel with carbon monoxide.