[Pb_6(H_2O)_2(cit)_4]·3H_2O和Pb(tar)(H_2O)_2两种柔性酸和铅的配位聚合物的水热合成与表征

Hydrothermal Synthesis and Characterization of Two Coordination Polymers of Flexible Acid and Lead:[Pb_6(H_2O)_2(cit)_4]·3H_2O and Pb(tar) (H_2O)_2

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=citricacid)及Pb(tar)(H2O)2(2)(tar=tartaricacid).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.

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） nm^3, 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 3 D 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） nm^3, Z =8, Rl =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.