5 research outputs found

    Синтеза, карактеризација и испитивање каталитичких својстава комплекса Zn(II)

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    In this study, a series of novel zinc complexes have been synthesised and thoroughly characterized. Two of the complexes were prepared from the ligands obtained from derivatives of 2-acetylthiazole, and another two from the derivative of Girard's reagents T and P. These complexes featured tridentate coordinating ligands of hydrazone with NNS or NNO donating atoms and were characterized by elemental analysis, spectroscopic techniques and single crystal XRD methods. In addition to these new complexes, the study also included a catalytic study of five analogues previously synthesized, each containing ligands with the same donor atom sets. The primary aim of this research was to evaluate the catalytic potential of these complexes in the coupling reaction of KA2, leading to the synthesis of tetrasubstituted propargylamines, which are commonly used as intermediates in organic synthesis, providing easy access to a wide range of structurally complex organic compounds. A number of model reactants were used to optimise the KA2 reaction conditions. To further investigate the catalytic activity of the Zn(II) complex, additional tests were then carried out on the most reactive compounds using a variety of substrate combinations. In order to better understand the electronic structure of the complexes and how it correlates with catalytic reactivity, the study employed density functional theory (DFT) calculations. Based on the Conceptual DFT framework the study derived several global molecular reactivity descriptors, including chemical potential (µ), hardness (η), softness (S), electronegativity (χ), and electrophilic index (ω). These descriptors provided valuable insights into how reactive and stable complexes are.U ovoj tezi, sintetisana je i detaljno okarakterisana serija novih kompleksa Zn(II). Dva kompleksa su dobijena polazeći od liganda derivata 2-acetiltiazola, a druga dva od derivata Žirarovih T i P reagenasa. Ovi kompleksi sadrže ligande na bazi tridentatnih hidrazona, sa NNO ili NNS donorskim setom atoma, i okarakterisani su elementalnom analizom, infracrvenom (IC) i nuklearno magnetno rezonantnom (NMR) spektroskopijom i metodom difrakcije rendgenskih zraka na monokristalima. Pored novih kompleksa Zn(II), studija je takođe uključila i pet prethodno sintetisanih analoga, koji sadrže ligande sa istim donorskim setom atoma. Glavni cilj ovog istraživanja bio je evaluacija katalitičkog potencijala kompleksa Zn(II), u reakciji keto-amin-alkin (KA2) kuplovanja, koja kao proizvod daje tetrasupstituisane propargilamine. Propargilamini se najčešće koriste kao intermedijeri u organskim sintezama, omogućavajući lak pristup širokom spektru kompleksnih organskih jedinjenja. Prilikom optimizacije KA2 reakcije korišćeni su različiti model sistemi. Kako bi se dodatna ispitala katalitička aktivnost kompleksa Zn(II), za nejreaktivnija jedinjenja, se potom pratio uticaj promenom polaznih supstrata na reaktivnost. DFT proračuni su izvedeni da bi se razjasnila elektronska struktura ispitivanih kompleksa Zn(II), odlično povezujući strukturu kompleksa sa njihovom katalitičkom aktivnošću. Na osnovu Konceptualne teorije funkcionala gustine, izračunati su globalni molekulski deskriptori reaktivnosti, kao što su hemijski potencijal (µ), tvrdoća (η), mekoća (S), elektronegativnost (χ) i indeks elektrofilnosti (ω). Ovi deskriptori su pružili uvid u to koliko su proučavani kompleksi reaktivni i stabilni

    Синтеза, карактеризација и DFT прорачуни бинуклеарног комплекса Mn(II) са шифовим базама

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    The Mn(II) complex was synthesized by the reaction of N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl)ethylidene)hydrazinyl)ethan-1-aminium chloride, HL1Cl (0.25 mmol), and MnCl2‧4H2O (0.25 mmol) in methanol. After complete dissolution of Mn(II) salt, NaN3 (1 mmol) was added. The mixture was stirred for 2 h at 60 °C. After slow evaporation of solvent in refrigerator for 14 days, pale orange crystals were obtained. The complex was characterized via elemental analysis, IR spectroscopy and X-Ray. Density functional theory (DFT) calculations at ZORA-M06-2X/TZP level of theory revealed weak ferromagnetic interactions between Mn(II) centers

    Correlating Structure and KA2 Catalytic Activity of Zn(II) Hydrazone Complexes

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    Two new Zn(II) complexes bearing tridentate hydrazone-based ligands with NNO or NNS donor atoms were synthesised and characterised by elemental analysis, infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies, and single crystal X-ray diffraction methods. These complexes, together with four previously synthesised analogues, having hydrazone ligands with a NNO donor set of atoms, were successfully employed as catalysts in the ketone-amine-alkyne (KA2) coupling reaction, furnishing tetrasubstituted propargylamines, compounds with unique applications in organic chemistry. DFT calculations at the CAM-B3LYP/TZP level of theory were performed to elucidate the electronic structure of the investigated Zn(II) complexes, excellently correlating the structure of the complexes to their catalytic reactivity

    Synthesis, Characterization, Catalytic Activity, and DFT Calculations of Zn(II) Hydrazone Complexes

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    Two new Zn(II) complexes with tridentate hydrazone-based ligands (condensation products of 2-acetylthiazole) were synthesized and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction methods. The complexes 1, 2 and recently synthesized [ZnL3(NCS)2] (L3 = (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium) complex 3 were tested as potential catalysts for the ketone-amine-alkyne (KA2) coupling reaction. The gas-phase geometry optimization of newly synthesized and characterized Zn(II) complexes has been computed at the density functional theory (DFT)/B3LYP/6–31G level of theory, while the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO and LUMO) energies were calculated within the time-dependent density functional theory (TD-DFT) at B3LYP/6-31G and B3LYP/6-311G(d,p) levels of theory. From the energies of frontier molecular orbitals (HOMO–LUMO), the reactivity descriptors, such as chemical potential (μ), hardness (η), softness (S), electronegativity (χ) and electrophilicity index (ω) have been calculated. The energetic behavior of the investigated compounds (1 and 2) has been examined in gas phase and solvent media using the polarizable continuum model. For comparison reasons, the same calculations have been performed for recently synthesized [ZnL3(NCS)2] complex 3. DFT results show that compound 1 has the smaller frontier orbital gap so, it is more polarizable and is associated with a higher chemical reactivity, low kinetic stability and is termed as soft molecule

    Synthesis, Characterization, Catalytic Activity, and DFT Calculations of Zn(II) Hydrazone Complexes

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    Two new Zn(II) complexes with tridentate hydrazone-based ligands (condensation products of 2-acetylthiazole) were synthesized and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction methods. The complexes 1, 2 and recently synthesized [ZnL3(NCS)2] (L3 = (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium) complex 3 were tested as potential catalysts for the ketone-amine-alkyne (KA2) coupling reaction. The gas-phase geometry optimization of newly synthesized and characterized Zn(II) complexes has been computed at the density functional theory (DFT)/B3LYP/6–31G level of theory, while the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO and LUMO) energies were calculated within the time-dependent density functional theory (TD-DFT) at B3LYP/6-31G and B3LYP/6-311G(d,p) levels of theory. From the energies of frontier molecular orbitals (HOMO–LUMO), the reactivity descriptors, such as chemical potential (µ), hardness (η), softness (S), electronegativity (χ) and electrophilicity index (ω) have been calculated. The energetic behavior of the investigated compounds (1 and 2) has been examined in gas phase and solvent media using the polarizable continuum model. For comparison reasons, the same calculations have been performed for recently synthesized [ZnL3(NCS)2] complex 3. DFT results show that compound 1 has the smaller frontier orbital gap so, it is more polarizable and is associated with a higher chemical reactivity, low kinetic stability and is termed as soft molecule. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)
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