Syntheses, characterizations and crystal structures of two lead(II) diphosphonates: Pb2[NH(CH2PO3)2] · 2H2O and Pb3[HO2C(CH2)3NH(CH2PO3)2]2 · 2H2O

Hydrothermal reactions of lead(II) acetate and HO2C(CH2)3N(CH2PO3H2)2 at 170 and 140 °C, respectively, resulted in two different lead diphosphonates, namely, Pb2[NH(CH2PO3)2] · 2H2O (1), in which the butyric acid moiety of the HO2C(CH2)3N(CH2PO3H2)2 has been cleaved and a novel layered compound, Pb3[HO2C(CH2)3NH(CH2PO3)2]2 · 2H2O (2). Their crystal structures have been determined by single crystal X-ray diffraction. In compound 1, the interconnection of the lead(II) ions by bridging amino-diphosphonate ligands leads to the formation of a 3D network. Compound 2 features an unusual triple-layer structure with the non-coordinated butyric acid moieties as pendant groups between the layers.