Two new lead(II) diphosphonates with second ligands as an intercalated species or a multidentate metal linker

Hydrothermal reactions of lead(II) acetate with N,N′-piperazinebis(methylenephosphonic acid) (H2O3PCH2N(C2H4)2NCH2PO3H2, H4L1) and 5-sulfoisophalic acid monosodium salt (NaH2SIP) or lead(II) acetate with isopropylimino-bis-(methylenephosphonic acid) ((CH3)2CHN (CH2PO3H2)2, H4L2) and succinic acid afforded two new lead(II) phosphonate hybrids, namely, Pb4(H2L1)(SIP)2(H2O)4·2H2O 1 and Pb4(L2)2·(HO2CH2CH2CO2H) 2. The structure of compound 1 features a 3D network formed by Pb(II) ions interconnected by H2L1 and the carboxylate–sulfonate SIP anions. The 3D network can be viewed as the neighboring layers of Pb4(SIP)2 being interconnected by H2L1 ligands to form a pillared layered architecture. The phosphonate groups of the diphosohonate ligands bridge the Pb(II) ions of the Pb4(SIP)2 layer to form a lead(II) phosphonate–sulfonate hybrid layer and the organic group of phosphonate ligand as pillars. In compound 2, the interconnection of the lead(II) ions via diphosphonate ligands lead to a 〈400〉 lead(II) diphosphonate layer. The succinic acid remains protonated and is located at interlayer space. The second ligand in compound 1 acts as a multidentate metal linker, whereas the succinic acid in compound 2 functions as an intercalated species in between the 2D layers.