The synthesis and X-ray structure analysis of Sn-2(HL)Cl .H2O, where HL3- is the anion of 1-hydroxyethane-1, 1-diphosphonic acid, are reported. The coordination polyhedra of two independent lin(II) atoms are the Sn(1)O2Cl and Sn(2)O-3 trigonal pyramids, in which one of the vertices is occupied by a lone electron pair (Sn-O, 2.144-2.218 Angstrom and Sn-Cl, 2.573 Angstrom). The pyramids are complemented by weaker Sn . . .O and Sn . . . Cl contacts to form severely distorted (3 + 3) octahedra. The SnO2Cl and SnO3 pyramids are linked by the HL3- bridging ligands into the [Sn-2(HL)Cl](6) cyclic molecules, which, in turn, are joined by additional Sn . . .O, Sn . . . Cl, O(H2O). . .O(L), and O(H2O). . . Cl contacts with each other and with crystallization water molecules into a three-dimensional framework. (C) 2001 MAIK "Nauka/Interperiodica".