Synthesis And Structure of N- and O-Donor Pyridazine-Based Ligands of Various Denticity
摘要
Three new pyridazine derivatives are synthesized and characterized: 3-chloro-6-(3,5-di-tert-butyl-1H-pyrazol-1-yl)pyridazine (L2), 3-(3,5-di-tert-butyl-1H-pyrazol-1-yl)-6-hydrazinopyridazine (L3), and 2-((2-(6-(3,5-di-tert-butyl-1H-pyrazol-1-yl)pyridazin-3-yl)hydrazineylidene)methyl)phenol (H2L4). Compounds L2 and L3 can act as chelate N-donor ligands, H2L4 can act as a polydentate N- and O-donor ligand. All compounds are described by the elemental analysis, powder X-ray diffraction (XRD), IR, electronic, and NMR NMR (1H, 13C) spectroscopic techniques, and their melting points are determined. The crystal structures of L2 and H2L4 compounds are determined by the single crystal XRD analysis. The powder XRD analysis reveals that the L2, L3, and H2L4 compounds are pure phases. The L2 and H2L4 compounds have the molecular structure. The structure of the latter consists of two crystallographically independent molecules forming dimers via pair intermolecular N–H⋯N hydrogen bonds (dN⋯N distances of 3.06 Å and 3.00 Å). A short intramolecular hydrogen bond is observed in the H2L4 molecule, which is confirmed by dO⋯N and dH⋯N distances of 2.66 Å and 1.9 Å at the sum of nitrogen and hydrogen atomic Bondi radii of 2.65 Å (RH + RN). In the L2 and H2L4 molecules, the N1 (pyrazole ring) and N3 (pyridazine ring) atoms are in the trans-position. From the electronic and 1H NMR spectroscopic data it follows that it is possible to completely deprotonate the H2L4 molecule with trimethylamine in acetonitrile and chloroform.