Novel tripodal ligands (R1N4CS)3CH, where R1 = Me, Ph, were synthesised by alkylation of 1-R-tetrazol-5-thioles with iodoform in alkaline media. These ligands were identified based on data of elemental analysis, nuclear magnetic resonance spectroscopy, thermal analysis, and X-ray diffraction analysis of single crystals.
Drawing the experience of 5-phenyl- and 5-pyridyltetrazoles, it was shown that classical nitration-reduction methods in combination with typical alkylation reactions of tetrazole derivatives can be used to obtain multitopic polynuclear tetrazole-containing ligands. Methods for the preparation of a number of previously undescribed polynuclear tetrazole derivatives, including those combining both tetrazole and pyridine rings in the molecule, have been developed. The composition and structure of the obtained compounds were determined by elemental analysis, single crystal X-ray diffraction, NMR and IR spectroscopy. For (5-(pyridin-2-yl)tetrazol-2-yl)(5-(pyridin-2-yl)tetrazol-1-yl)methane the crystalline structure was determined and it was found that this compound forms a 3D polymer framework due to non-classical hydrogen bonds. In its crystal structure there is a network of π – π stacking interactions between tetrazole rings of neighbouring molecules, as well as between pyridine rings.
Complexes [Сu(NCS)2L3], [Сu(NO3)2L4] and [Cu(NCS)2L4]·L have been prepared by direct synthesis involving the interaction of metallic copper, ammonium salts NH4X (Х = NCS, NO3) and 1-tert-butyl-1H-1,2,4-triazole (L). Their composition and structure were determined by elemental analysis, single crystal X-ray analysis, and IR spectroscopy (range of 4000–500 cm–1). All the complexes showed mononuclear structure. In them triazole acts as a monodentate ligand, being coordinated by the N4 atom of the heterocycle. The NCS– and NO–3 anions display monodentate N- and O-coordination, accordingly. In [Сu(NCS)2L3], copper(II) cation has square-pyramidal environment of nitrogen atoms of two ligands L and two thiocyanate anions in the basal sites, and one nitrogen atom of ligand L in the apical position. In complexes [Сu(NO3)2L4] and [Cu(NCS)2L4]·L, copper(II) cations are octahedrally surrounded by nitrogen atoms of ligand L in the equatorial sites and by O or N atoms of corresponding anions in the axial positions.
A novel facile method for the synthesis of 1-iso-propyl-1H-1,2,4-triazole (L) is described. This method is based on alkylation of 1,2,4-triazole with isopropyl alcohol in sulfuric acid media. It allows to synthesize the target product selectively with a yield of near 98 %. New coordination compounds [CuL2(Н2О)2Cl2] and [СuL4Cl2] were synthesized by the interaction of 1-iso-propyl-1H-1,2,4-triazole with copper(II) chloride dihydrate. Composition and structure of prepared complexes were studied by elemental analysis, X-ray diffraction analysis and IR spectroscopy. Both coordination compounds were found to be mononuclear complexes with octahedral coordination of copper atoms. Ligand L shows monodentate coordination through the triazole ring N4 atom. The analysis of the changes observed in the IR-spectrum of L under coordination with CuII atom was carried out. It was shown that IR spectroscopy can be used in order to study some structural peculiarities of azole complexes, in particular presence of bounded or coordinated water molecules and hydrogen bonds as well as localization of coordination bonds.
