Coordination Polymer and Monomer with the Cd(NO3)2 Fragment Containing 2-Amino-5-Bromopyridine: Synthesis, Structures, NMR Study, and Luminescence Properties

The reactions of Cd(NO3)2 ⋅ 4H2O with 2-amino-5-bromopyridine (Аbp) afford compounds [Cd(NO3)2(Аbp)(H2O)]n (I) and [Cd(NO3)2(Abp)2(H2O)2] (II). The structures of both complexes are determined by single-crystal X-ray structure analysis (CIF files CCDC nos. 1938624 (I) and 1959680 (II)). Compound I is a coordination 1D polymer in which two chelate-bonded \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{NO}}_{3}^{ - }$$\end{document} groups act as bridges. The coordination polyhedron of the octacoordinated central cadmium atom in compound I consists of seven oxygen atoms (one oxygen atom of water and six atoms of the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{NO}}_{3}^{ - }$$\end{document} groups) and one nitrogen atom of Abp, being a triangular dodecahedron. Complex II is a mononuclear molecule in which the octahedral coordination polyhedron of Cd is formed by four oxygen atoms of two water molecules and two \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{NO}}_{3}^{ - }$$\end{document} groups and two oxygen atoms of two molecules of the Abp cycle. In both complexes, the amino group of Abp is not involved in coordination with the metal. Compound I is studied by 1H, 31C, and 15N NMR spectroscopy of a solution of the polymer complex in CD3CN, and the most substantial difference in the chemical shifts of the bound and free Abp ligands is observed in the 15N NMR spectra (37 ppm). According to the data of luminescence spectroscopy, compounds I and II exhibit an emission in a range of 430–690 nm.