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

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

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

Poly[[diaqua[μ5-(R,S)-2-({2-[(1,2-di­carboxyl­atoeth­yl)amino]­eth­yl}amino)­butane­dioato]cobaltate(III)sodium] di­hydrate]

In the asymmetric unit of the title coordination polymer, {[CoNa(C10H12N2O8)(H2O)2]·2H2O}n, the CoII ion is coord­inated in a distorted octa­hedral environment, defined by two N atoms and four carboxyl­ate O atoms. Two CoII ions and two 2-({2-[(1,2-dicarboxyl­atoeth­yl)amino]­eth­yl}amino)­butane­dio­ate (EDDS) ligands form a dimeric complex dianion [Co2(EDDS)2]. These dimeric units are connected via Na+ ions, forming a three-dimensional polymeric structure. In the crystal, the ligand N—H groups and the coordinated and solvent water mol­ecules are involved in inter­molecular N—H⋯O and O—H⋯O hydrogen bonding, reinforcing the three-dimensional polymeric structure