Water spontaneously ionizes into hydroxide anions and hydronium cations. Mixed anion compounds exist that contain hydride with other anions. These cations are linked to the sulfate anions via hydrogen bonds. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . The salt also dissociates into its constituent anions and cations. Water ionizes into hydronium (HO) cations and hydroxide (OH) anions. Salts exist in many different colors, which arise either from the anions or cations. The anions and cations are each six-coordinate. Quaternary ammonium salts exist with many kinds of anions. The cations associate with the anions in the solution. Polycyclic aromatic compounds characteristically reduce to the radical anions. Monodentate ligands include virtually all anions and all simple Lewis bases. The Krapcho decarboxylation is the chemical reaction of esters with halide anions. The sulfides tend to undergo hydrolysis to form derivatives containing bisulfide (SH) anions. Its oxides form a family of anions known as silicates.