Volume 4: Organic and Organometallic Compounds presents a cross section of applications in organic and organometallic chemistry in two parts. Chapters 1 to 6 are devoted to the fundamentals whereas chapters 7 and 8 cover applications to organic and organometallic compounds, either available as pure compounds or present in complex mixtures. Chapter 1 describes the theory for organic mass spectrometry, building on and complementing material in Volume 1. The themes for Chapter 2 are the structures and properties of gas-phase ions of conventional, distonic, and non-covalent complexes. Chapter 3 covers methodology used in study of gas-phase ions. Chapters 4 and 5 turn to mechanisms of both unimolecular and bimolecular reactions of ions and include topics in stereochemistry and radical chemistry. Chapter 6 contains a number of articles on the formation and reactivity of metal ion complexes and organometallic cations and anions, drawing connections with molecular recognition, catalysis and organic synthesis. Chapter 7 deals with the structure determination of organic compounds, including chiral compounds and natural products. In chapter 8 are contributions that provide illustrative examples of the determination of organic compounds present at low levels in complex samples that originate from various natural and biological sources. Included is an article on the determination of explosives.