Dipotassium hydrogencarbonate fluoride monohydrate.

Single crystals of the title compound, K2(HCO3)F·H2O, were obtained as a secondary product after performing flux synthesis experiments aimed at the preparation of potassium rare earth silicates. The basic building unit of the structure is an (HCO3)(H2O)F zigzag chain running parallel to [001]. Both types of anions as well as the water mol-ecules reside on mirror planes perpendicular to [010] at y = 0.25 and y = 0.75, respectively. Linkage between the different constituents of the chains is provided by O-H⋯O and O-H⋯F hydrogen bonding. The K(+) cations are located between the chains and are coordinated by two F and five O atoms in form of a distorted monocapped trigonal prism.