Synthesis, structure and thermal stability properties of the transition metal carboxylate complexes containting scorpionate-liked ligands with pyrazolyl derivatives

Abstract

Two novel supramolecular complexes [Co 2 (HL 1 ) 2 (seb)H 2 O]·2.5H 2 O (1) and [Cu(H 2 L 2 )(ox)]·H 2 Ox·MeOH (2) (H 2 L 1 =2,6-di-(5- phenyl-1H-pyrazol-3-yl)pyridine, H 2 seb = sebacic acid, H 2 L 2 = 2,6-di-(5-methyl-1H-pyrazol-3-yl)pyridine, H 2 Ox=oxalic acid) based on pyrazolyl derivatives as ligands have been designed and synthesized. The complexes were characterized by elemental analysis, IR and UV-Vis spectroscopy, powder X-ray diffraction and single-crystal X-ray diffraction. Structural analysis reveals that in complexes 1 and 2, the coordination modes of the ligands H 2 L 1 and H 2 L 2 are different. The H 2 L 1 ligand generates a μ 2 -η 1 -η 1 -η 1 -η 1 coordination environment in 1; however, the H 2 L 2 ligand forms a μ 1 -η 1 -η 1 -η 1 coordination motif in 2. The coordination modes of the structurally similar sebacic and oxalic acids are also different, with the sebacic acid acting as a monodentate ligand and the oxalic acid as bidentate bridging ligand. 1 and 2 form 2D net and 1D chain structures, respectively, through C-H···O, O-H···O and N-H···O hydrogen bonds. In addition, the thermal stability of the two title complexes has been evaluated and is discussed in detail.