[Pb6(H2O)2(cit)4]·3H2O和Pb(tar)(H2O)2两种柔性酸和铅的配位聚合物的水热合成与表征

在水热条件下, 合成了2个含柔性配体柠檬酸和酒石酸的二价铅配位聚合物Pb6(H2O)2(cit)4]·3H2O(1)(H3cit=citric acid)及Pb(tar)(H2O)2(2)(tar=tartaric acid). 用红外光谱、差热-热重、元素分析、粉末X射线衍射及单晶X射线衍射等手段对化合物进行了表征. 化合物1属三斜晶系, P1空间群, a=0.97053(19) nm, b=0.9764(2) nm, c=1.0955(2) nm, α=109.016(3)°, β=98.380(3)°, γ=92.136(3)°, V=0.9671(3) nm3, Z=2, R1=0.0420, wR2=0.1049, GOF=1.064. 在化合物1的不对称结构单元中, 有3个铅离子以及2个柠檬酸阴离子和2个游离的水分子. 铅离子分别以4, 5, 7配位与柠檬酸配合形成了中性的三维骨架结构. 化合物2属于正交晶系, Pbca空间群, a=1.39739(6) nm, b=0.64922(2) nm, c=1.80354(10) nm, V=1.63620(13) nm3, Z=8, R1=0.0283, wR2=0.0649, GOF=1.014. 在化合物2的不对称结构单元中, 有1个铅离子、1个酒石酸分子和1个水分子, 六配位的铅和酒石酸形成了一维外消旋的无限长链, 链与链之间通过氢键连接成一个三维超分子结构. 在化合物1和2中, 两种配体均出现了α羟基和α羧基螯合的配位模式, 铅的6s孤电子对均显示了立体化学活性, 使配位键分布于半球区域.

Hydrothermal Synthesis and Characterization of Two Coordination Polymers of Flexible Acid and Lead: [Pb6(H2O)2(cit)4]·3H2O and Pb(tar)(H2O)2

Two coordination polymers Pb6(H2O)2(cit)4]·3H2O(1)(H3cit=citric acid) and Pb(tar)(H2O)2(2)(tar=tartaric acid) were synthesized under hydrothermal conditions and characterized via IR, TG-DTA, C, H, N elemental analysis, XRD and single crystal X-ray diffraction analysis. There are three Pb, two cit ligand and two free water molecules in the asymmetry unit in complex 1. The Pb ions in complex 1 coordinate to cit anions with the coordination number of 4, 5, 7 to form a neutral 3D framework. Complex 1 crystallizes in the triclinic system, space group P1 with a=0.97053(19) nm, b=0.9764(2) nm, c=1.0955(2) nm, α=109.016(3)°, β=98.380(3)°, γ=92.136(3)°, V=0.9671(3) nm3, Z=2, R1=0.0420, wR2=0.01049, GOF=1.064. In the asymmetry unit of complex 2, there are a six-coordinated Pb, a tar ligand and a water molecule. Complex 2 has a structure of extended racemic ladder-like chain, these chains are assembled by complicated H-bonds to 3D supramolecular structure. It crystallizes in the orthorhombic system, space group Pbac with a=1.39739(6) nm, b=0.64922(2) nm, c=1.80354(10) nm, V=1.63620(13) nm3, Z=8, R1=0.0283, wR2=0.0649, GOF=1.014. In both complexes 1 and 2, the α hydroxyl and α carboxyl adopt a chelate mode, and the 6s lone pair of electrons of Pb has a stereochemistry activity resulting the distribution of the bonds in a hemisphere.