Pure and Applied Chemistry

Introduction: Knowledge of the properties and reactivities of stable inorganic radicals was obtained decades ago through gas-phase studies of various oxides of halogens, sulfur, and nitrogen. More recently, pulse radiolysis and flash photolysis techniques developed in the 1960s made it possible to study short-lived radicals, such as hydrated electrons, hydrogen atoms, and hydroxyl radicals. Because of the high time-resolution of these techniques, absorption spectra and redox properties of these inorganic radicals could be determined. The interest in radicals increased when it was shown that superoxide, or dioxide(1-), is formed in vivo. The discovery that in aerobic organisms enzymes catalyze the disproportionation of this radical resulted in new areas of research, such as radical biology and radicals in medicine. Interest in simple radicals was further boosted most recently by the remarkable observation that the radical nitrogen monoxide is formed enzymatically from the amino acid arginine. Radicals are important in a variety of catalytic processes and in the atmospheric gas and liquid phases; furthermore, a substantial number of inorganic radicals have been observed in interstellar gas clouds.

Contents:

1. Introduction

2. Definitions

3. Nomenclature

• 3.1. Introduction
• 3.2. Coordination nomenclature
• 3.2.1. Selection of the central atom
• 3.2.2. Radicals with net charges
• 3.2.3. Attached atoms or groups of atoms
• 3.2.4. The radical dot
• 3.2.5. Examples
• 3.3. Substitutive nomenclature