The monorgaph is dedicated to the development of a new approach to the synthesis of multinuclear copper compounds, which consists in oxidative dissolution of copper powder in the presence of copper(II) halides in non-aqueous solution of organic ligands on air. The difference of the proposed approach from the widely used direct synthesis with ammonium salts is the use of copper(II) halides, which simultaneously act as a controlled source of anions and a primary oxidant of metallic copper. The optimal conditions for the synthesis of copper(II) pyrazole-containing complexes were selected. It was shown that the optimal molar ratio between reagents for the synthesis of µ3-oxocentric trinuclear copper(II) pyrazole-containing complexes is 1:1:2 (copper:copper(II) halide:pyrazole ligand). The final products are formed after the stage of formation of known trinuclear copper(I) compounds. The formation of mainly tetranuclear compounds [Cu4(µ4-O)(µ2-X)6(L1)4] (X – Cl, Br; L1 – 3,5-dimethyl-1Н-pyrazole, 1Н-pyrazole) occurs when the molar ratio is changed to 1:2:3. Most of the first synthesized coordination compounds have a molecular structure and consist of neutral particles. X-ray powder diffraction confirms the crystalline nature of some analyzed samples and the formation of individual compounds. Thermogravimetric analysis of some compounds showed that these complexes are stable to a temperature of 100 ˚С.
Contents
1. Investigation of the peculiarities of oxidative dissolution of metallic copper in the presence of Cu2+ ions in non-aqueous solutions of pyrazole ligand
2. Structure of the pyrazole-containing coordination compounds К1–К8
2.1. Structure [Cu(Hpz)2Cl2](К1)
2.2. Structure [Cu(Hdmpz)3Br2] (К2), [Cu2(µ2-Br)(µ2-4Br35dmpz)(Hdmpz)4Br2]ꞏ2CHCl3 (К3), [Cu3(µ3-OH)(µ2-Br)3(µ2-4Br35dmpz)(Hdmpz)5Br]ꞏCHCl3 (К4)
2.3. Structure of trinuclear metal-cyclic complexes [Cu3(µ3-OH)(µ2-Cl)(µ Ipz)3Clꞏ2CH3CN]2 (К5) та [Cu3(µ3-OH)(µ2-Br)2(µ-Ipz)3]n (К6)
2.4. Structure of tetranuclear complexes [Cu4(µ4-O)(µ2-Br)6(Hpz)4] (К7) та [Cu4(µ4-O)(µ2-Cl)6(Hdmpz)4] (К8)
3. Brief conclusions
Research Objectives and Topics
The primary objective of this monograph is to investigate the oxidative dissolution processes of metallic copper in the presence of various copper(II) halides and pyrazole ligands. The research seeks to identify optimal synthesis and crystallization conditions for diverse multinuclear coordination compounds, while determining how initial system composition, solvent choice, and external factors influence the structure and properties of the final complexes.
- Mechanisms of oxidative dissolution of metallic copper in non-aqueous pyrazole-containing systems.
- Synthesis and structural characterization of copper(II) coordination complexes with pyrazole and substituted pyrazole ligands.
- Influence of experimental parameters (temperature, solvent, reagent ratio) on coordination complex formation.
- Analysis of crystal structures, molecular geometry, and supramolecular interactions using X-ray diffraction and Hirshfeld surface analysis.
Excerpt from the publication
1. Investigation of the peculiarities of oxidative dissolution of metallic copper in the presence of Cu2+ ions in non-aqueous solutions of pyrazole ligand
The increased interest of scientists in multinuclear compounds requires the development of new methods for their synthesis. Recently, the direct synthesis method has been used in this area. One such approach is the oxidative dissolution method.
It has been noted that in some cases multinuclear copper compounds are formed by the oxidative dissolution of metallic copper powder with aqueous solutions of copper(II) halides in the presence of pyrazole. Several multinuclear copper(I) and (II) complexes have been isolated and identified. However, the available literature does not contain data on the influence of the composition of such starting systems and synthesis conditions on the composition, structure and properties of the obtained multinuclear complexes.
Thus, the following tasks were set:
1) to study the products formed in the process of oxidative dissolution of metallic copper powder with chloride, bromide and dihydrate of divalent copper chloride in aqueous solutions of some pyrazole ligands;
2) to study the effect of the initial composition of the system on the composition of the final products;
3) to select the optimal conditions for the synthesis of multinuclear coordination compounds: molar ratio of the starting reagents, temperature for the synthesis and solvent;
4) to establish optimal conditions for the crystallization of products.
Summary of Chapters
1. Investigation of the peculiarities of oxidative dissolution of metallic copper in the presence of Cu2+ ions in non-aqueous solutions of pyrazole ligand: This chapter outlines the synthesis approach involving the oxidation of metallic copper and establishes the experimental goals for exploring various chemical systems and synthesis conditions.
2. Structure of the pyrazole-containing coordination compounds К1–К8: This chapter provides an in-depth structural characterization of the synthesized compounds K1 through K8, utilizing X-ray crystallography, IR spectroscopy, and Hirshfeld surface analyses to explore their molecular and crystal environments.
3. Brief conclusions: This final section summarizes the outcomes of the investigation into the oxidative dissolution systems and the successful identification and structural determination of the new pyrazolate coordination complexes.
Keywords
Coordination compounds, Copper(II) complexes, Pyrazole ligands, Oxidative dissolution, Multinuclear complexes, X-ray crystallography, Crystal structure, Hirshfeld surface, Supramolecular interactions, Metal-cyclic complexes, Molecular geometry, Coordination polyhedron, Ligand synthesis, Elemental analysis, IR spectroscopy
Frequently Asked Questions
What is the primary scientific focus of this monograph?
This work focuses on the synthesis and structural analysis of copper(II) coordination compounds containing pyrazole ligands, specifically exploring the process of oxidative dissolution of metallic copper in non-aqueous media.
What are the central thematic fields addressed in the research?
The research intersects inorganic coordination chemistry, synthetic methodology, crystallographic analysis, and the investigation of intermolecular interactions using Hirshfeld surface methods.
What is the core research goal?
The core goal is to determine how varying the initial components, solvents, and reaction conditions affects the structural composition and properties of new multinuclear copper coordination compounds.
Which specific scientific methods are employed?
The methodology includes oxidative dissolution synthesis, elemental analysis, IR spectroscopy, X-ray diffraction for structural determination, and computational analysis (Hirshfeld surfaces) to probe intermolecular contacts.
What topics are covered in the main body of the work?
The main body details the experimental procedures for synthesis, systematic structural characterization of complexes K1–K8, thermogravimetric analysis of thermal stability, and detailed topological analysis of bonding and crystal packing.
Which keywords best characterize the study?
The study is characterized by terms such as coordination chemistry, multinuclear copper complexes, pyrazole ligands, X-ray crystallography, and Hirshfeld surface analysis.
How do the researchers define the structural difference between K5 and K6?
K5 exists as centrosymmetric dimeric fragments joined by chloride bridges, whereas K6 forms polymer chains of trinuclear units interconnected by bridging bromine atoms, with differing symmetries and coordination environments.
What is the significance of the Hirshfeld surface analysis applied to these complexes?
This analysis provides quantitative data on intermolecular contacts—such as H...H, H...Br, and I...Cl interactions—which are crucial for understanding the packing, stability, and supramolecular arrangement of the crystal structures.
What role does the oxidation state of copper play in the reaction mechanism?
The transition between zero-valent metallic copper and copper(II) ions leads to the formation of copper(I) intermediates, which are subsequently oxidized by atmospheric oxygen, mediating the formation of the observed multinuclear structures.
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- Y. M. Davydenko (Autor:in), O. S. Vynohradov (Autor:in), I. A. Gural'skiy (Autor:in), I. O. Fritsky (Autor:in), V. O. Pavlenko (Autor:in), Y. M. Davydenko (Autor:in), 2024, Coordination Compounds of Copper (II) with Pyrazole Ligands, München, GRIN Verlag, https://www.grin.com/document/1508817
