Noncovalently‐bonded 2D‐3D Metal‐organic Frameworks via Assembly of Zn(Ac)2 with 3, 5‐Dimethylpyrazole and Carboxylate Ligands

Abstract

AbstractFour zinc(II) complexes, namely, Zn(Hdmpz)2(L1)2 (1) (Hdmpz = 3, 5‐dimethylpyrazole, HL1 = trichloroacetic acid), Zn(Hdmpz)2(L2)2 (2) (HL2 = 2, 4‐dichlorophenoxyacetic acid), [Zn2(μ‐dmpz)2(Hdmpz)2(L3)2] (3) (HL3 = 1‐naphthylacetic acid), and [Zn(Hdmpz)2(L4)2]·H2O (4) (HL4 = indole‐3‐acetic acid) were prepared and structurally characterized by different techniques including elemental analysis, IR spectroscopy, TG, and single‐crystal X‐ray diffraction analysis. The complexes display 2D to 3D structures with tetrahedral to pentagonal coordination around the central zinc atom. The X‐ray studies suggested that 1, 2, and 4 are mononuclear complexes, whereas 3 is a centrosymmetric dinuclear complex. The pyrazole ligand is coordinated in both terminal as well as a bridging fashion in the dinuclear moiety but the pyrazole ligand in the mononuclear complexes is coordinated only in monodentate terminal fashion with its neutral N group. The carboxylate groups behave as monodentate ligands in 1–3, whereas the carboxylate in 4 functioned as both monodentate and chelating bidentate ligand. On the basis of X‐ray crystallographic study the rich intra‐ and intermolecular weak interactions such as classical hydrogen bonds, C–H···O, CH3···O, CH–Cl, Cl–Cl, C–H···π, CH2–π, CH3–π, O–π, and π–π are analyzed. All these noncovalent interactions help to assemble the discrete complexes into high‐dimensional ordered superamolecular structures.