 In the Mond process, nickel tetracarbonyl is used to produce pure nickel.In organometallic chemistry, metal carbonyls serve as precursors for the preparation of other organometalic complexes.Metal carbonyls are toxic by skin contact, inhalation or ingestion, in part because of their ability to carbonylate hemoglobin to give carboxyhemoglobin, which prevents the binding of O2.