Syntheses, structures, and properties of zinc(II), cadmium(II), cobalt(II), and manganese(II) coordination polymers with tetraiodoterephthalate

The coordination chemistry of a rigid periodinated ligand, 2,3,5,6-tetraiodo-1,4-benzenedicarboxylic acid (H2BDC-I4), with a series of transition metal ions has been explored to afford five new coordination polymers {[M(BDC-I4)(MeOH)4](H2BDC-I4)(MeOH)2}n (M = ZnII for 1, CdII for 2, CoII for 3 and MnII for 4) and {[Mn(BDC-I4)(MeOH)4](DMF)}n (5). All these complexes have been characterized by elemental analysis, IR spectroscopy, thermogravimetric (TG) analysis, and X-ray crystallography. Single-crystal X-ray diffraction reveals that complexes 1–4 are isostructural and have a one-dimensional chain structure. Upon the addition of the solvent DMF, the infinite linear chain array in 4 is converted to a 1-D wave-like chain motif in 5 with a different space group (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ P\overline{1} $$\end{document} for 4 and P21/c for 5). The difference between structures 1–4 and 5 can be attributed to the coordination mode of carboxylate changing from trans to cis fashion. The ZnII and CdII complexes 1 and 2 display similar emissions in the solid state, which essentially are intraligand transitions.