Two new layered lead(II) diphosphonates with 1,3,5-benzenetricarboxylate ligands as an intercalated species or a multidentate metal linker

Hydrothermal reactions of lead(II) carbonate with 1,3,5-benzenetricarboxylic acid (H3BTC) and butylimino-bis(methylenephosphonic acid) (CH3CH2CH2CH2N(CH2PO3H2)2, H4L1) or lead(II) acetate with H3BTC and isobutylimino-bis(methylenephosphonic acid) (Me2CHCH2N(CH2PO3H2)2, H4L2) afforded two novel lead(II) carboxylate phosphonate hybrids, namely, Pb5(HL1)2(L1)·H3BTC 1 and Pb4(BTC)(L2)(CH3CO2)(H2O)2·1.5H2O 2. The structure of compound 1 contains a <002> lead(II) diphosphonate hybrid layer formed by Pb(II) ions interconnected by HL1 and L1 anions. In compound 2, the interconnection of Pb(II) ions through bridging diphosphonate L2 anions lead to the formation of the <200> lead(II) diphosphonate 2D layer. In compound 1, the 1,3,5-benzenetricarboxylic acid acts as an intercalated species whereas in compound 2, the 1,3,5-benzenetricarboxylate anion adopts a hexadentate chelating and bridging coordination mode.