PNICTIDE OXIDES - A UNIQUE CLASS OF COMPOUNDS

Layered pnictide oxides are an unusual class of compounds which have r eceived little attention. The characteristic feature of these material s is the presence of pnictogen and oxygen atoms which are not bonded t o 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 alo ng with transition metals. This Comment discusses structure and bondin g in this small group of compounds. Additionally, magnetic and electro nic properties of many of the transition metal pnictide oxide compound s are presented.