It is composed of pyrophosphate anion and sodium ions. But most anions are large, as is the most common Earth anion, oxygen. Simple oxides are characterized by O as the main anion and primarily ionic bonding. It is a salt composed of the sodium cation and the azanide anion. It is a salt composed of a sodium cation (Na) and a bicarbonate anion (HCO). Coordination polyhedra are geometric representations of how a cation is surrounded by an anion. A DM plant generally consists of cation, anion, and mixed bed exchangers. Nucleophilic alkylating agents deliver the equivalent of an alkyl anion (carbanion). Antimonic acid exists only as the hydrate , forming salts as the antimonate anion . The salts of the cyanide anion are known as cyanides. It is a rare example of a stable salt of the superoxide anion. The only important polyiodide anion in aqueous solution is linear triiodide, . The k' pathway implicates a reaction between the doubly charged anion (RCHO) and the aldehyde. The molecule is isoelectronic with the carbonate anion, . All phosphate fertilizers are obtained by extraction from minerals containing the anion PO.