Two isomeric lead(II) carboxylate-phosphonates: syntheses, crystal structures and characterizations

Two isomeric layered lead(II) carboxylate-phosphonates of N-(phosphonomethyl)-N-methyl glycine ([MeN(CH2CO2H) (CH2PO3H2)] = H3L), namely, monoclinic (Pb3L2H2O)-H-. I and triclinic (Pb3L2H2O)-H-. 2, have been synthesized and structurally determined. Compound I synthesized by hydrothermal reaction at 150degreesC is monoclinic, space group C2/c with a = 19.9872(6), b = 11.9333(l) and c = 15.8399(4) Angstrom, beta = 110.432(3)degrees, V = 3540.3(l) Angstrom(3), and Z = 8. The structure of compound I features a <400> layer in which the lead(II) ions are bridged by both phosphonate and carboxylate groups. The lattice water molecules are located between the layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Compound 2 with a same empirical formula as compound I was synthesized by hydrothermal reaction at 170degreesC. It has a different layer structure from that of compound 1 due to the adoption of a different coordination mode for the ligand. It crystallizes in the triclinic system, space group P (1) over bar with cell parameters of a = 7.1370(6), b = 11.522(1), c = 11.950(1) Angstrom, alpha = 110.280(2), beta = 91.625(2), gamma = 95.614(2)degrees, V = 915.3(1) Angstrom(3) and Z = 2. The structure of compound 2 features a <020> metal carboxylate-phosphonate double layer built from ID lead(II) carboxylate chains interconnected with ID lead(II) phosphonate double chains. XRD powder patterns of compounds I and 2 indicate that each compound exists as a single phase. (C) 2004 Elsevier Inc. All rights reserved.