Three novel calcium complexes of clodronic acid were prepared and their structures determined by single‐crystal X‐ray diffractometry. Previously, a monomeric structure, [Ca{Cl2C(PO3H)2}(H2O)5] (1), has been determined, but the new structures are polymeric: [{Ca2[Cl2C(PO3)2](H2O)6}·4.5H2O]n (2), [{Ca2Na0.5[Cl2C(PO3)2](H2O)8}Cl0.5·4H2O]n (3) and [{Ca5[Cl2C(PO3)2]2(H2O)15}(NO3)2·1.5H2O]n (4); and they provide new, important information about the binding abilities of clodronic acid. Compounds 2−4 crystallise in the triclinic crystal system, the space group being P$\bar 1$ with Z = 2. Compound 2 consists of Ca atoms and Cl2MBP ligands connected to one‐dimensional chains. The chains are held together by hydrogen bonds formed by aqua ligands and lattice water molecules. The structure of 3 consists of similar calcium clodronate chains forming two‐dimensional layers through additional, six‐coordinate Na atoms. Compound 4 consists of two‐dimensional calcium clodronate layers, the calcium atoms are connected by Cl2MBP− and aqua ligands. The nitrate groups and lattice water molecules lie between the layers and hold them together. The layered compounds 3 and 4 reveal substantial porosity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Four new zinc and cadmium bisphosphonates [{NaZn(Cl2CP2O6H)(H2O)5}]n (1), [{Cd2(Cl2CP2O6)(H2O)4}.H2O]n (2), [{Zn(Cl2CP2O6Pri2)(H2O)3}.H2O]n (3), and [{Cd2(Cl2CP2O6Pri2)2(MeOH)2(H2O)2}.H2O]2 (4) have been prepared and their crystal structures determined by single-crystal X-ray diffractometry. Two bisphosphonate ligands were used: clodronate, (dichloromethylene)bis(phosphonate) and its symmetrical P,P'-diisopropyl ester derivative. The structure of the Zn complex 1 is three-dimensional, consisting of one-dimensional Zn-clodronate chains connected to the three-dimensional network by Na+ ions. The structure of Cd complex 2 consists of double layers, and a unique bond was found between the Cd2+ cation and a Cl atom of clodronate. Zn complex 3 consists of one-dimensional chains, but the binding of the bisphosphonate ligands is unique: in 3 the bisphosphonate ligand is only bidentate. Compound 4 is a tetramer, and hydrogen bonds hold the tetramers together, forming a layered structure.

The title compound, [Sr{Cl2C(PO3H)2}(H2O)5], is a monomer, the Sr atom being seven‐coordinated by one chelating clodronate ligand and five aqua ligands. The coordination polyhedron can be described as a distorted monocapped trigonal prism. This compound is isostructural with hydrated calcium clodronate, [Ca{Cl2C(PO3H)2}(H2O)5], described previously [Nardelli, Pelizzi, Staibano & Zucchi (1983). Inorg. Chim. Acta, 80, 259–271].