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.