Synthese neuer Tetrazole, N-Alkyltetrazole und Übergangsmetall(II)komplexe mit Tetrazolat-Liganden

The synthesis, UV-Vis-absorption spectroscopy and electrochemical investigations of seven new tetrazolate complexes is reported. Single-crystal XRD data reveal the formation of octahedral configured complexes. With the tridentate ligand PydtzH2 {2,6-di(1H-tetrazol-5-yl)pyridine} the complexes [Co(Pydtz)(H2O)Py2], [Co(Pydtz)(H2O)2Py]2H2O, [Ni(Pydtz)Py3]2Py, [Cu(Pydtz)(H2O)2Py] and [Zn(Pydtz)(H2O)Py2]Py were obtained. From the ligand (BTFT)H {5-[3,5-bis(trifluoro¬methyl)phenyl]-1H-tetrazole}, the first complex with a polymeric structure [Cu(BTFT)2Py2]n could be synthesized and fully characterised, including XRD, EPR spectroscopy and magnetic measurements.

Na3(PPh4)(Pydtz)212H2O and (Ph4As)2Pydtz5H2O were synthesized in order to have well soluble salts of the Pydtz2--dianion for complex synthesis and large cations for possible anionic tetrazolate complexes. They were characterised using 1H-, 13C-NMR and single-crystal XRD. The crystal-structures contain several middle to strong hydrogen bonds.

A further goal was the synthesis of new N-alkylated tetrazoles. Ten new N-alkylated tetrazoles were synthesized: (1-N,1-N')-Me2(Pydtz), (1-N,2-N')-Me2(Pydtz), (1-N,2-N')-(n-Pent)2Pydtz, (2-N,2-N')-(n-Pent)2Pydtz, (2-N,2-N')-(2-But)2(Pydtz), (2-N,2-N')-(n-Pent)2(1,3-BTB), (1-N,2-N')-(n-Pent)2(1,3-BTB), (2-N,2-N')-(2-But)2(1,4-BTB), (2-N)-Me(BTFT) and (2-N)-(2-But)(BTFT) with 1,x-BTBH2 = 1,x-di(1H-tetrazol-5-yl)benzole, x = 3 or 4. All tetrazole derivatives were characterised by 1H-, 13C-NMR and some additionally by single-crystal XRD or 15N-NMR. Unfortunately those ligands have very weak ligand strength and could not successfully be coordinated with MII-transition metal cations, in contrast to 2N-MePytz = 2-(2N-1H-tetrazol-5-yl)pyridine, from which one complex, [Cu(2N-MePytz)2Cl2]H2O, was synthesized. [Cu(2N-MePytz)2Cl2]H2O had to be recrystallized from DMF and not from pyridine, because this delivered the tetrazole-free complex [CuCl2Py2]. Due to the weak binding of the N-alkylated tetrazole.

Furthermore a new tetrazole was synthesized from the starting material 2,3-pyridinedicarbonitrile. Interestingly not the expected product 2,3-di(1H-tetrazol-5-yl)pyridine was achieved, though 2-(1H-tetrazol-5-yl)pyridine-3-carbonitrile {PyCN(tzH)} was synthesized, confirmed through recurring synthesis, even with different methods, and characterised with single-crystal XRD, 1H- and 13C-NMR.