Synthesis, structure and characterization of two Pb(II) phosphonates with layered or 3D structures

Hydrothermal reactions of lead(II) acetate and N-cyclohexylimino-bis(methylenephosphonic acid) (C6H11N(CH2PO3H2)2, H4L1) or N,N′-bis(phosphonomethyl)-6-aminocaproic acid (HO2C(CH2)5N(CH2PO3H2)2, H5L2), respectively, resulted in two different new lead diphosphonates, namely, Pb2L1 · H2O (1) and Pb2[HL2] (2). Their crystal structures have been determined by single crystal X-ray diffraction. The structure of compound 1 contains a 〈0 0 1〉 lead(II) diphosphonate hybrid layer formed by Pb(II) ions interconnected by L1 anions. Such layers are further interlinked by van der Waals force into a supramolecular structure. In compound 2, the Pb(II) ions are interconnected by the –N(CH2PO3H)(CH2PO3) and –CO2 groups of the HL2 anions forming an organic–inorganic hybrid layer. These layers are further interlinked by the –(CH2)5 groups of the HL2 anions into a 3D structure.