PNICTIDE OXIDES - A UNIQUE CLASS OF COMPOUNDS

Layered pnictide oxides are an unusual class of compounds which have received little attention. The characteristic feature of these materials is the presence of pnictogen and oxygen atoms which are not bonded to each other and are considered to be anions. This class of compounds is made up of ternary pnictide oxides of alkaline or rare earth metals, and quaternary pnictide oxides of alkali or alkaline earth metal along with transition metals. This Comment discusses structure and bonding in this small group of compounds. Additionally, magnetic and electronic properties of many of the transition metal pnictide oxide compounds are presented.