Silver diaquacobalt(II) catena-borodiphosphate(V) hydrate, (Ag(0.79)Co(0.11))Co(H(2)O)(2)[BP(2)O(8)]·0.67H(2)O

The structure of the title compound, (Ag(0.79)Co(0.11))Co(H(2)O)(2)[BP(2)O(8)]·0.67H(2)O is isotypic to that of its recently published counterparts AgMg(H(2)O)(2)[BP(2)O(8)]·H(2)O and (Ag(0.57)Ni(0.22))Ni(H(2)O)(2)[BP(2)O(8)]·0.67H(2)O. It consists of infinite borophos­phate helical ribbons [BP(2)O(8)](3−), built up from alternate BO(4) and PO(4) tetra­hedra arranged around the 6(5) screw axes. The vertex-sharing BO(4) and PO(4) tetra­hedra form a spiral ribbon of four-membred rings in which BO(4) and PO(4) groups alternate. The ribbons are connected through slightly distorted CoO(4)(H(2)O)(2) octa­hedra whose four O atoms belong to the phosphate groups. The resulting three-dimensional framework is characterized by hexa­gonal channels running along [001] in which the remaining water mol­ecules are located. The main difference between the Mg-containing and the title structure lies in the filling ratio of Wyckoff positions 6a and 6b in the tunnels. The refinement of the occupancy rate of the site 6a shows that it is occupied by water at 67%, while the refinement of that of the site 6b shows that this site is partially occupied by 78.4% Ag and 10.8% Co, for a total of 82.2%. The structure is stabilized by O—H⋯O hydrogen bonds between water mol­ecules and O atoms that are part of the helices.