On a Way to New Types of the Hybrid Polyazomethine-Pyrazolate Metal Pseudomacrobicyclic Complexes: the Synthesis and Structure of Their Ligand Synthones

Abstract

3-Acetylpyrazole hydrazone, its formyland carboxymethyl-containing analogs and the bis-pyrazolyl azine derivative were obtained in moderate yields by condensation under vigorous reaction conditions and characterized using elemental analysis, LC-mass spectrometry, IR, 1H and 13C{1H} NMR spectroscopies, and X-ray diffraction crystallography (for a bis-pyrazolyl azine compound). The X-rayed molecule occupies a special position with an inversion centre; beside planarity of its C=N–N=C moiety, the corresponding C–N and N–N bond lengths suggest the absence of a conjugation in this diazomethine fragment, whereas those in the pyrazolyl cycles clearly suggest a delocalization of the electron density. The azine molecules form hydrogen-bonded layers that are parallel to the crystallographic plane (100). Although these molecules are almost planar, π-stacking interactions between them are absent, and 2D layers are connected via van-der-Waals C–H...π interactions at the distances of 2.695 A. The compounds obtained were described to be suitable organic synthones for the synthesis of monoand binuclear hybrid polyazomethine-pyrazolate metal pseudomacrobicyclic complexes.