Crystal structure of poly[μ-aqua-bis(μ(3)-2-methylpropanoato-κ(4) O:O,O′:O′)dipotassium]

The structure of the title compound, [K(2)(C(4)H(7)O(2))(2)(H(2)O)](n), is composed of stacked sandwiches, which are formed by cation–oxygen bilayers surrounded by methyl­ethyl hydro­phobic chains. These sandwiches are held together by van der Waals inter­actions between the methyl­ethyl groups. The methyl­ethyl groups are disordered over two positions with occupancies 0.801 (3):0.199 (3). The potassium cations are coordinated by seven O atoms, which form an irregular polyhedron. There is a water mol­ecule, the oxygen atom of which is situated in a special position on a twofold axis (Wyckoff position 4e). The water H atoms are involved in O(water)—H⋯O(carbox­yl) hydrogen bonds of moderate strength. These hydrogen bonds are situated within the cation–oxygen, i.e. hydro­philic, bilayer.