Synthesis and Crystal Structure of Copper(II) 9-Azametallacrowns-3 with 4-Iodopyrazole
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MISTRY OF MACROCYCLIC AND METALLOCYCLIC COMPOUNDS
Synthesis and Crystal Structure of Copper(II) 9-Azametallacrowns-3 with 4-Iodopyrazole O. S. Vynohradova, *, V. A. Pavlenkoa, I. O. Fritskya, I. A. Gural’skiya, and S. Shovab aDepartment
of Chemistry, Taras Shevchenko National University of Kyiv, Kiev, 01601 Ukraine Petru” Institute of Macromolecular Chemistry, Iasi, 700487 Romania *e-mail: [email protected]
b“Poni
Received April 25, 2020; revised May 12, 2020; accepted May 27, 2020
Abstract—Two novel copper(II) polynuclear complexes with deprotonated 4-iodopyrazole (Ipz) of composition [Cu3(μ3-OH)(μ-Ipz)3Cl2 · 2CH3CN]2 (1) and [Cu3(μ3-OH)(μ-Ipz)3Br2]n (2) have been synthesized and isolated in crystalline state. Crystal and molecular structure of both compounds has been studied by single crystal X-ray diffraction. The structure of complex 1 consists of dimerized 9-azametallacrown-3 fragments Cu3(μ3-OH)(μ-Ipz)3Cl2 · 2CH3CN connected between each other by chlorine anions. The dimeric molecules are united into polymeric chains with the help of hydrogen bonds between the hydrogen atoms of μ3OH-group and the chlorine anions of the neighboring fragment. Complex 2 is crystallized as polymeric structure, consisting from the trinuclear fragments Cu3(μ3-OH)(μ-Ipz)3Br2 united by bridging bromine atoms. It is established that in the case of complex 1 the Cu(II) coordination number is complemented up to 5 on account of acetonitrile molecule, whereas in complex 2 the pentacoordinated geometric environment of copper(II) ions is formed by two bridging bromine anions belonging to the neighboring structure subunit. Keywords: copper, copper complexes, crystal structure, pyrazole, X-ray crystallography, metallacrown DOI: 10.1134/S0036023620100228
INTRODUCTION Pyrazole-containing ligands exhibit a marked propensity to versatile coordination upon formation of polynuclear compounds. They can form structures of various nuclearities, ranged from mononuclear complexes to polynuclear exchange clusters and metallacycles. As a result of introduction of additional potentially coordination groups in the pyrazole ring the number of donor centers can be increased that can facilitate formation of different types of coordination compounds [1–3]. During the last years, the copper trinuclear pyrazole-containing complexes of azametallacrown type attracted significant attention of researchers, as they can indicate nontrivial magnetic properties [4–6], can act as catalysts of peroxide oxidation of alkanes [7]. In the mentioned trinuclear structures with azametallacrown motif, a substitution of the terminal monodentate ligands is possible, and on their substitution on bidentate ligands the latter can act as bridging ligands between two trinuclear structure units [8]. It is known that the redox active copper trinuclear clusters can be found in the active sites of some metalloproteins, such as ascorbate oxidase, laccase, and ceruloplasmin [9]. By this reason, obtaining of mixed valence complexes Cu37 + (CuII2 CuIII ) , Cu34 + (Cu I2CuII ), Cu35+ (CuIC
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