Synthesis, Structures And Spectroscopic Properties Of 5-Substituted Tetrazolate Coordination Complexes

In recent years, there have been increasing research interests focused on tetrazolate complexes. This is mainly because tetrazole compounds, as polydentate N-donor ligands with diverse coordination modes, can build a variety of metal-organic coordination polymers. Recently, Sharpless et al. reported a simple, safe and environmentally friendly process for the preparation of 5-substituted 1H-tetrazoles, through the [2+3] cycloaddition reactions of nitriles with azide in the presence of zinc salt as Lewis acid in water. This dissertation mainly focuses on the in situ hydro(solvo)thermal syntheses, structures and luminescencent properties of series of tetrazolate-based coordination complexes. The thesis is divided into three chapters.In the first chapter, the research background is concisely introduced by highlighting recent advances of crystal engineering on metal-organic complexes, and illustrating the influencing factors in the designed syntheses and structures of metal-organic complexes, including temperature, pH value, solvents, anions and template agents. In addition, summary of research progresses on the syntheses, structures, properties and applications of tetrazolate complexes in the past few years, are presented. Finally, the aims and advances of this work are also outlined.The second chapter, focuses on the systematic investigation of the influencing factors such as temperature, pH value, solvents, anions and template agents on the hydro(solvo)thermal in situ generated tetrazolate coordination architectures. A series of new metal-organic complexes: [Cu(pzta)2 (H2O)2 ] (1), [Cu(pzta)2(NH3)2] (2), [Cu(pzta)2 ]n (3), [Cu(pzta)2 ]n (4), {[Cu2 (pzta)2 CN](DMF)} n (5), [Cu 3 (pzta)2 Br]n (6) [pzta = pyrazinyl tetrazolate] have been achieved by hydrothermal synthesis from pyrazinecarbonitrile and sodium azide or pyrazinyl tetrazolate ligand with different coppe salts. Complexes 1 and 2 contain similar Cu(pzta)2 mononuclear unit with the difference of the axial ligands. Complex 3 is a 1D chain polymer. Complex 4 and 5 formed the 2D sheet stuctures, respectively. Interestingly, the wave-shaped 2D architecture of complex 5 contains 1D channel. Complex 6 is a 3D structure constructed from copper-pyrazinyl-tetrazolate helices linked via CuBr chains. The dimensionalities of complexes 1-6 span from mononuclear (1, 2), one- (3), two- (4,5) to three- (6) dimensions, which indicates that the synthetic conditions play important roles in the framework formation of the in situ generated tetrazolate complexes. In chapter 3, six new coordination compounds containing carboxylate-tetrazolate ligands are obtained by solvo(hydro)thermal in situ reactions using dicyano reactants: [Ni(tacapy)(H 2 O) 2 ]2 (7), [Co(tacapy)(H2 O)3]2 (8), [Co(tacapy)(H2 O) 4 ]2 (9), [Mn(tacapy)(H2O) 4 ]n (10), [Cd(tacapy)]n (11) (tacapy = tetrazolate carboxylate pyridine), [Cd(tacapz)]n (12) (tacapz = tetrazolate carboxyl pyrazine). Complex 7-9 are zero-dimensional binuclear structures, which are extended into 3D supramolecular architectures via intermolecular hydrogen bonding in their crystal packings. Complex 7 and 8 can be simplified to a NaCl–like six-connected pcu hydrogen-bonding network, while complex 9 can be seen as a (6,10) connected hydrogen-bonding network with the symbol of (34 ?4 8 ?5 3)(38? 4 18 ?5 14 ?6 5). Complex 10 is a one-dimensional polymeric chain. Complex 11 and 12 are both three-dimensional polymers. Complex 11 can be simplified to a six-connected network with the symbol (36?66?73), and complex 12 is a four-connected network with the symbol 42 ?6 3?8. An interesting phenomenon occurs in the syntheses and structures of the six complexes, that in these reactions only one cyano group of the dicyano reactant undergoes cycloaddition to generate to tetrazolate group, while the other cyano group is always hydrolyzed into carboxlate group. Furthermore, complexes 11 and 12 exhibit strong photoluminescence.