Novel chromium (III) complexes with N4-donor ligands as catalysts for the coupling of CO2 and epoxides in supercritical CO2

Cuesta-Aluja, Laia; Djoufak, M.; Aghmiz, Ali; Rivas, Raquel; Christ, L.; Masdeu‐Bultó, Anna M.

doi:10.1016/j.molcata.2013.10.021

Cited by 29 publications

(17 citation statements)

References 36 publications

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“…Even if most of Schiff base ligands are N 2 O 2 ligands, some N 4 derivatives are developed. Nevertheless, N 2 (NH 2 ) 2 Schiff bases have been reported as well as some of their complexes but, to our knowledge no Zn helical complexes have been reported yet.…”

Section: Introductionmentioning

confidence: 92%

Unexpected Structure of a Helical N₄‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

et al. 2018

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A new Zn‐N4‐Schiff base L=((±)‐trans‐N,N’‐Bis(2‐aminobenzylidene)‐1,2‐diaminocyclohexane) complex was synthesized and fully characterized, showing an unexpected self‐assembled double‐stranded helicate structure. The X‐ray crystal analysis of the Zn2L2 complex ((C40H44N8Zn2,CH2Cl2, a=14.2375(3) Å, b=16.7976(4) Å, c=16.1613(4) Å, monoclinic, P21/n, Z=4) shows a centrosymmetrical structure in which zinc atoms are in distorted tetrahedral environments, revealing an M‐ (R, R) left‐handed helicity in its asymmetric unit. However, it was observed that this dinuclear complex is thermodynamically unstable in the presence of small water amounts and undergoes demetallation into free N4‐Schiff base ligand and ZnO nanoparticles. This hydrolysis process was thoroughly identified and monitored through detailed 1H NMR, DOSY NMR analysis. The reaction mechanism of this demetallation event was elucidated by using the DFT method, involving an activation energy smaller than 13 kcal/mol. Besides, a theoretical mechanism of the demetallation process is given for the first time.

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Section: Introductionmentioning

confidence: 92%

Unexpected Structure of a Helical N₄‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

et al. 2018

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“…In this regard, transition metal complexes (especially Schiff bases and porphyrins complexes) are particularly promising. [28][29] Salen-type compounds have been introduced very early by North [18] and Zhang, [19] then porphyrins by Ema [30] and, more recently, Schiff bases with 4 nitrogen atoms (BS4N) by Christ and Masdeu-Bulto. [28] Some of the systems involving metal complexes and QAS operate at room temperature and at atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

Advantages of Covalent Immobilization of Metal‐Salophen on Amino‐Functionalized Mesoporous Silica in Terms of Recycling and Catalytic Activity for CO₂ Cycloaddition onto Epoxides

et al. 2021

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Dedicated to the memory of Professor Michel CheNi II and Mn III Schiff base complexes (Salophen-Ni and Salophen-MnCl) bearing a pending carboxylic group were prepared and characterized. Both complexes were grafted onto a mesoporous amino-functionalized SBA-15 silica, by formation of an amide function between the propylamine groups of the support and the carboxylic acid functions of the salophen ligand (corresponding respective to 1.30 wt.% of Ni and 1.06 wt.% of Mn). The co-catalytic behaviour of the free and grafted complexes was then evaluated in the CO 2 cycloaddition reaction onto styrene oxide, using tetra-butylammonium bromide ( nÀ Bu 4 NBr) as the main catalyst. In homogeneous conditions, the Mn III Schiff base complex and the Ni II one, to a lesser extent, behave as efficient co-catalysts for this reaction (styrene conversion of 100 % and 65 % respectively after 3 h at 120°C, under 15 bars of CO 2 ). Upon immobilization at the surface of the aminofunctionalized SBA-15, we showed that the co-catalytic activity of the less efficient one, i. e. Ni 2 + salophen complex, could be enhanced (reaching a full conversion after 7 h), hence highlighting a potential synergistic effect between the unused amine functions of the support and the Ni 2 + salophen cocatalyst. Both salophen complexes were successfully re-used in homogeneous conditions or after their immobilization without any appreciable loss of activity. This work is only a first step towards a completely heterogeneous catalytic system, in which the tetraalkylammonium halide catalyst and the metal-salophen co-catalyst will both be covalently anchored on the same support.

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“…Usually, metal-based complexes display higher reactivity than organocatalysts for the coupling reaction. As a result of the diversity of the metal across the periodic table and the organic ligands of different structures, miscellaneous metal complexes based on aluminum , magnesium [33][34][35][36], chromium [37][38][39][40][41][42], cobalt [43][44][45][46][47][48], iron [49][50][51][52][53], and rare earth metals [54,55] have been innovated for the coupling reaction of CO 2 with epoxides. Of many metal complexes, aluminum complexes have been drawing attention due to their low price, easy availability, and the superior selectivity for the cyclic carbonate over polymeric products [56].…”

Section: Introductionmentioning

confidence: 99%

Syntheses, Characterization, and Application of Tridentate Phenoxyimino-Phenoxy Aluminum Complexes for the Coupling of Terminal Epoxide with CO2: From Binary System to Single Component Catalyst

Zhang

Wang

Xiang³

et al. 2021

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A series of binuclear aluminum complexes 1–3 supported by tridentate phenoxyimino-phenoxy ligands was synthesized and used as catalysts for the coupling reaction of terminal epoxide with carbon dioxide. The aluminum complex 1, which is catalytically inactive toward the coupling of epoxide with CO2 by itself, shows moderate activity in the presence of excess nucleophiles or organic bases at high temperature. In sharp contrast to complex 1, bifunctional complexes 2 and 3, which incorporate tertiary amine groups as the built-in nucleophile, are able to efficiently transform terminal epoxide with CO2 to corresponding cyclic carbonates as a sole product by themselves at 100 °C. The number of amine groups on the ligand skeleton and the reaction temperature exert a great influence on the catalytic activity. The bifunctional complexes 2 and 3 are also active at low carbon dioxide pressure such as 2 atm or atmospheric CO2 pressure. Kinetic studies of the coupling reactions of chloropropylene oxide/CO2 and styrene oxide/CO2 using bifunctional catalysts under atmospheric pressure of CO2 demonstrate that the coupling reaction has a first-order dependence on the concentration of the epoxide.

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Novel chromium (III) complexes with N4-donor ligands as catalysts for the coupling of CO2 and epoxides in supercritical CO2

Cited by 29 publications

References 36 publications

Unexpected Structure of a Helical N₄‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

Unexpected Structure of a Helical N₄‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

Advantages of Covalent Immobilization of Metal‐Salophen on Amino‐Functionalized Mesoporous Silica in Terms of Recycling and Catalytic Activity for CO₂ Cycloaddition onto Epoxides

Syntheses, Characterization, and Application of Tridentate Phenoxyimino-Phenoxy Aluminum Complexes for the Coupling of Terminal Epoxide with CO2: From Binary System to Single Component Catalyst

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Novel chromium (III) complexes with N4-donor ligands as catalysts for the coupling of CO2 and epoxides in supercritical CO2

Cited by 29 publications

References 36 publications

Unexpected Structure of a Helical N4‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

Unexpected Structure of a Helical N4‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

Advantages of Covalent Immobilization of Metal‐Salophen on Amino‐Functionalized Mesoporous Silica in Terms of Recycling and Catalytic Activity for CO2 Cycloaddition onto Epoxides

Syntheses, Characterization, and Application of Tridentate Phenoxyimino-Phenoxy Aluminum Complexes for the Coupling of Terminal Epoxide with CO2: From Binary System to Single Component Catalyst

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Unexpected Structure of a Helical N₄‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

Unexpected Structure of a Helical N₄‐Schiff‐Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies

Advantages of Covalent Immobilization of Metal‐Salophen on Amino‐Functionalized Mesoporous Silica in Terms of Recycling and Catalytic Activity for CO₂ Cycloaddition onto Epoxides