Low‐Oxidation‐State Main Group CompoundsUpdate based on the original article by Charles L. B. Macdonald and Bobby D. Ellis,Encyclopedia of Inorganic ChemistrySecond Edition, © 2005, John Wiley & Sons, Ltd.

AbstractThe synthesis and chemistry of compounds containing groups 1, 2, and 13‐15 elements in unusually low oxidation states or valence states is presented. In general, the oxidation or valence state of an element influences the chemistry of the compounds in which the atom is found. For the main group elements, compounds containing elements in lower‐than‐usual oxidation or valence states exhibit significantly different structural features, modes of bonding, and chemistry than is observed for compounds containing the element in a more typical oxidation state. The elements of the s‐block form a limited number of low‐oxidation‐state compounds and the elements of groups 16‐18 are generally found in the lowest available oxidation state. Thus, this article provides an overview of the following classes of low‐valent main group species: the chemistry of group 2 elements in the +1 oxidation state, the chemistry of group 13 elements in oxidation states lower than +3, the chemistry of group 14 elements in oxidation states lower than +2, and the chemistry of the group 15 elements in oxidation states lower than +3. Numerous exemplary modes of reactivity are presented, and the utility of some low‐oxidation‐state compounds as catalysts or precursors to materials is acknowledged.