A second triclinic polymorph of (1-ammonio-1-phosphono­eth­yl)phospho­nate

The asymmetric unit of the second polymorph of the title compound, C2H9NO6P2, contains one mol­ecule existing as a zwitterion. The N atom of the ammonio group is protonated and one of the phospho­nic acid groups is deprotonated. Bond lengths and angles are similar in both polymorphs. Besides the differences in cell parameters, the most significant structural difference between this structure and that of the first polymorph [Dudko, Bon, Kozachkova, Tsarik & Pekhno (2008 ▶), Ukr. Khim. Zh. 74, 104–106] is the presence of strong symmetric hydrogen bonds between neighbouring phospho­nate groups. H atoms involved in these hydrogen bonds are located at inversion centres and O⋯O distances are observed in the range 2.458 (5)–2.523 (5) Å. These bonds and additional O—H⋯O and N—H⋯O hydrogen bonds inter­link the mol­ecules, giving a three-dimensional supromolecular network

trans-Bis[(1-ammonio­pentane-1,1-di­yl)diphospho­nato-κ2 O,O′]diaqua­copper(II)

In the title compound, [Cu(C5H14NO6P2)2(H2O)2], the CuII atom occupies a special position on an inversion centre. It exhibits a distorted octa­hedral coordination environment consisting of two O,O′-bidentate (1-ammonio­pentane-1,1-di­yl)diphospho­nate anions in the equatorial plane and two trans water mol­ecules located in axial positions. The ligand mol­ecules are coordinated to the CuII atom in their zwitterionic form via two O atoms from different phospho­nate groups, creating two six–membered chelate rings with a screw-boat conformation. The CuO6 coordination polyhedron is strongly elongated in the axial direction with 0.6 Å longer bonds than those in the equatorial plane. Intra­molecular N—H⋯O hydrogen bonding helps to stabilize the mol­ecular configuration. The presence of supra­molecular —PO(OH)⋯O(OH)P— units parallel to (100) and other O—H⋯O and N—H⋯O hydrogen bonds establish the three-dimensional set-up

Diaqua­bis­(dihydrogen 3-aza­niumyl-1-hy­droxy­propyl­idene-1,1-di­phos­phon­ato-κ2 O,O′)cobalt(II)

The asymmetric unit of title compound, [Co(C3H10NO7P2)2(H2O)2], contains one half-mol­ecule of the complex. The CoII atom is located on an inversion centre and displays a distorted octa­hedral coordination geometry defined by four O atoms of two 3-aza­niumyl-1-hy­droxy­propyl­idene-1,1-bis­phospho­nato ligands in the equatorial plane and two water mol­ecules located in axial positions. The ligand mol­ecules, which exist in a zwitterionic state, form two six-membered chelate rings with chair conformations. In the crystal, mol­ecules are inter­linked by O—H⋯O and N—H⋯O hydrogen bonds, forming a three-dimensional supra­molecular structure

Bis[(1-ammonio­ethane-1,1-di­yl)diphospho­nato-κ2 O,O′]diaqua­nickel(II) nona­hydrate

The title compound, [Ni(C2H8NO6P2)2(H2O)2]·9H2O, exhibits a slightly distorted octa­hedral coordination environment around the NiII atom. It contains two mol­ecules of 1-amino­­ethyl­idenediphospho­nic acid in the zwitterionic form, coord­inated via O atoms from two phospho­nate groups and creating two six-membered chelate rings. Two water mol­ecules in cis positions complete the coordination environment of the NiII atom. The title compound contains nine partly disordered solvent water mol­ecules, which create a three-dimensional network of strong O—H⋯O and N—H⋯O hydrogen bonds

Poly[[tri-μ-aqua-dodecaaquatris(μ3-1-hydroxyethylidene-1,1-diphosphonato)tricalcium(II)tripalladium(II)] pentahydrate]

The asymmetric unit of the title compound, {[CaPd{CH3OHC(PO3)2}(H2O)5]·5/3H2O}n, consists of one half of the complex [Pd{CH3OHC(PO3)2}]2− anion (point group symmetry m..), one Ca2+ cation [site symmetry (.2.)] that is surrounded by three water molecules (one of which is on the same rotation axis) and by three disordered lattice water molecules. The anions form a trinuclear metallocycle around a crystallographic threefold rotation axis. The cations are related by a twofold rotation axis to form a [Ca2(H2O)10]2+ dimer. The slightly distorted square-planar coordination environment of the PdII atoms in the complex anions is formed by O atoms of the bidentate chelating phosphonate groups of the 1-hydroxyethylidene-1,1-diphosphonate ligands. In the crystal, cations are bound to anions through —Ca—O—P—O— bonds, as well as through O—H...O hydrogen bonds, resulting in a three-dimensional polymer. The structure is completed by five disordered solvent molecules localized in cavities within the framework

(μ-Methylenediphosphonato-κ4O,O′:O′′,O′′′)bis[(ethylenediamine-κ2N,N′)palladium(II)] tetrahydrate

The title compound, [Pd2(C2H8N2)2(CH2O6P2)]·4H2O, comprises of a binuclear molecule (point group symmetry 2), with a twofold rotation axis running through the central C atom of the methylenediphosphonate (MDP) anion. The PdII atom has a square-planar coordination environment defined by the N atoms of a bidentate ethylenediamine (en) ligand and two O atoms of the bridging MDP anion. In the crystal structure, metal complexes are arranged in layers parallel (001) and are sandwiched between layers containing disordered water molecules of crystallization. Extensive intralayer hydrogen bonds of the type N—H...O in the metal complex layer and O—H...O in the water layer, as well as O—H...O hydrogen bonds between the two types of layers, lead to the formation a three-dimensional network structure. The two lattice water molecules are each equally disordered over two positions