Three complexes obtained by the reaction of Pr(Ⅲ) or Nd(Ⅲ) salts with 5-methyl-2-pyrazinecarboxylic acid(Hmpca) are structurally determined by single-crystal X-ray diffraction.Complex [Pr(mpca-)3(H2O)2]2·6H2O(1) is composed of dinuclear Pr(Ⅲ) units with two metal centers bridged by two anionic mpca-ligands in a κ3O,O':O' bridging mode.Complexes [Pr(mpca-)3]n(2) and [Nd(mpca-)3]n(3) are isostructures,and they consist of polymeric chains based on Ln(Ⅲ) and mpca-ligands.Each pair of adjacent metal centers is linked by three mpca-molecules in a κ3N,O:O bridging mode.
Two new transition metal compounds, [Mn(dpa)2(tmd)2]n (1, H2dpa = 4-hydroxy-phenyl-acetic acid, tmd = 4,4-trimethylenedipyridine) and [Co4(dpa)6(tmd)4(H2O)4]n·nH2O·nCl2 (2), have been synthesized by hydrothermal synthesis. Compound 1 crystallizes in the monoclinic system, space group P21/n with a = 9.828(3), b = 17.493(5), c = 11.616(4), β = 110.146(6)o, V = 1874.9(10)3, C42H42MnN4O6, Mr = 753.74, Z = 2, Dc = 1.335 g/cm3, μ = 0.406 mm–1, F(000) = 790, the final R = 0.1047 and wR = 0.2021 for 2698 observed reflections (I > 2σ(I)). Compound 2 crystallizes in the monoclinic system, space group P21/c with a = 11.7214(13), b = 17.1582(19), c = 24.625(3), β = 103.055(3)o, V = 4824.4(9)3, C100H104Cl2Co4N8O23, Mr = 2094.55, Z = 2, Dc = 1.443 g/cm3, μ = 0.809 mm–1, F(000) = 2180, the final R = 0.0550 and wR = 0.0673 for 4104 observed reflections (I > 2σ(I)). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. The structural analyses show that the two compounds are both one-dimensional chain structures. However, compounds 1 and 2 form threedimensional supramolecular structures by hydrogen bonds, respectively.
