any coordination or complex compound consisting of a heavy metal such as nickel, cobalt, or iron surrounded by carbonyl (CO) groups. Some common metal carbonyls include: tetracarbonylnickel Ni(CO)4, pentacarbonyliron Fe(CO)5, and octacarbonyldicobalt Co2(CO)8. In general, the metal carbonyls are produced by direct action of carbon monoxide on the finely divided metal. They are used in the preparation of metals of exceptionally high purity and as catalysts in organic syntheses.
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