Structures And Properties Of Organically Templated Thiocyanatocadmates

As an important branch of hybrid orangic-inorganic materials, the design and synthesis of novel organically templated halometallates has attracted much attention. Because of their structural diverdisy, and their potential applications in optics, electrical conductivity and magnetism. By employing various organic bases as the countercations, a large number of novel halometallates have been obtained over the last twenty years. It is worth mentioning that the structures of the halometallates are still unpredictable when a new organically templated agent is used. Since the hybrid formation process is rather complicated, and dominated by many factors such as the geometry of the metal ion, the coordination mode of the halide or pseudohalide ion, the form, size, and charge of the organic base, as well as the detailed experimental conditions. At present, one of the investigations in our group is focused on the structural characterization of novel organically template thiocyanatocadmates. It is also the main research direction of this paper.By room temperature evaporation method, we chose the chained aliphatic amine and pyridine amine as cationic organic molecules, through adjusting the p H level of the reaction solution, successfully synthesing six kinds thiocyanatocadmates with different structures. All of the compounds characterized by power/single-crystal X-ray diffraction, IR, UV, TG, Fluorescence and so on. The main research results as follows:1. We chose chained aliphatic amine as counteraction, in order to investigating the diversity structure with these organic amines as organic templating agent. Successfully synthesing three compounds. They are [H₂（tmen）][Cd（SCN）₄]（1）, [H₂（tmba）][Cd2（SCN）₆]（2）, and [H₂（teen）][Cd₂（SCN）₆]（3）. The compound 1 is a chained thiocyanatocadmate, and compound 2 is a ribboned thiocyanatocadmate. It is interesting that the structure of H₂（tmen）²⁺ and H₂（tmba）²⁺ are very similar, the difference is the number of C between the two N atoms. We find that the number of C atoms between the two N atoms in the templating agent controls the width of the 1-D linear chain. With the increase of the number of C atoms from 2（tmen） to 4（tmba）, the width of the chain increase from 1（single chain） to 2（double chain）. Compound 3 is the extremely rare example of 3-D thiocyanatocadmate.2. We chose chained aliphatic amine and pyridine amine as counteraction, Synthesing three compounds introduced Cl-, CH₃COO-, and SO₄^2-. They are [H₂（tmen）][Cd₃Cl₆（SCN）₂]（4）, [H（amp）][Cd（SCN）2（CH₃COO）]（5）, and [H（abp）]4[Cd（SCN）₄]SO₄×H₂O（6）. The introduction of cadmiumsalt anion and acid anion as the second connector enrich the framework of thiocyanatocadmates. Compound 4 is another rare example of 3-D thiocyanatocadmate. Compounds 5 and 6 have good fluorescence properties.