Iron carbonyl complexes reactions with Lewis bases

Although CO is an exceedingly weak Lewis base, one of its most important properties is the ability to act as a donor ligand toward transition metals, giving metal carbonyls. For example, nickel metal reacts with CO to form Ni(CO)4, and iron reacts under more forcing conditions to give Fe(CO)5 many other carbonyl complexes are also known. The ability of CO to form bonds to transition-metal atoms is discussed in detail in Chapter 22, and catalytic reactions whereby CO is incorporated into organic compounds are discussed in Chapters 23 and 24. 

---