Cobalt(<scp>iii</scp>) complexes with tridentate hydrazone ligands: protonation state and hydrogen bond competition

Vrdoljak, Višnja; Pavlović, Gordána; Hrenar, Tomica; Rubčić, Mirta; Siega, Patrizia; Dreos, Renata; Cindrić, Marina

doi:10.1039/c5ra22068h

Cited by 18 publications

(14 citation statements)

References 67 publications

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“…1a). In order to sustain the electro-neutrality of the complex molecule, the Co(III) is octahedrally bonded via two ONO tridentate ligands of different protonation state 45 . Four oxygen atoms occupy the equatorial plane while imino nitrogen atoms are axially positioned in the octahedron with bond distances of 1.874 (3) Å and 1.864(3) Å for Co1-N1 and Co1-N3, respectively.…”

Section: Resultsmentioning

confidence: 99%

Chemical fixation of carbon dioxide catalyzed via cobalt (III) ONO pincer ligated complexes

et al. 2019

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Chemical insertion of carbon dioxide into epoxides under ambient conditions has become one of the most important methods for the construction of cyclic organic carbonates. Various active salen, salophen, and phenolate ligand based complexes have been reported for the synthesis of cyclic organic carbonates. Here we demonstrate a series of ONO pincer type cobalt (III) complexes as efficient catalysts for the cycloaddition of carbon dioxide to epoxides in neat conditions at atmospheric pressure with and without co-catalyst. A turnover number of up to 200,000 under atmospheric pressure is achieved. Moreover, the in situ generated complex shows high activity and the catalyst can be reused for at least 11 cycles without any decline in catalytic performance.

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Section: Resultsmentioning

confidence: 99%

Chemical fixation of carbon dioxide catalyzed via cobalt (III) ONO pincer ligated complexes

et al. 2019

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“…It is well-known that aroylhydrazone ligands can experiment with tautomerism related to its protonation . It is remarkable that both Tb 2 Cl and Dy 2 CF 3 SO 3 simultaneously display both keto and imine tautomers along the two branches of the H 2 daps 2– ligands of these two complexes.…”

Section: Resultsmentioning

confidence: 99%

Tb₂, Dy₂, and Zn₂Dy₄ Complexes Showing the Unusual Versatility of a Hydrazone Ligand toward Lanthanoid Ions: a Structural and Magnetic Study

et al. 2018

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Three dinuclear complexes, [Tb(Hdaps)(CHOH)(HO)](Cl) (TbCl), [Dy(Hdaps)(Cl)(CHOH)(HO)]Cl (DyCl), and [Dy(Hdaps)(HO)](CFSO) (DyCFSO), as well as the heterohexanuclear compound [ZnDy(daps)(Hdaps)(Cl)(OH)(CHOH)(HO)] (ZnDy) (Hdaps: 2,6-bis(1-salicyloylhydrazonoethyl)pyridine), which crystallize with different lattice molecules, show their hexa- or heptadentate hydrazone ligands acting with hitherto unknown μ-κ:κ, μ-κ:κ:κ, μ-κ:κ:κ:κ, or μ-κ:κ:κ:κ bridging modes. The single X-ray crystal structures of the dinuclear complexes show nine-coordinated N O environments for lanthanoid atoms in TbCl and DyCFSO, with distorted geometries, between spherical capped square antiprism and muffin-like, while the dysprosium atoms in DyCl are eight-coordinated, with distorted triangular dodecahedron geometries. In the case of ZnDy, both eight-coordinated, O and O Cl, as well as nine-coordinated N O environments coexist in the crystal structure, with biaugmented trigonal prism, triangular dodecahedron, and muffin-like pseudogeometries. The magnetic study of all the complexes shows that none of the pure samples behaves as a single molecular magnet (SMM) and that the quantum tunnel cannot be removed by dilution of any of the dinuclear complexes, but except in diluted [YDy(Hdaps)(Cl)(HO)]Cl (DyCl@Y), behaves as a weak field induced SMM. The heterohexanuclear ZnDy complex also lacks slow relaxation of the magnetization.

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“…The band characteristic for the CO group at ca. 1650 cm –1 (seen in the IR spectra of H 2 L) is shifted to 1545–1556 cm –1 in the spectra of the complexes, suggesting coordination of hydrazidato ligand through the carbonyl oxygen atom …”

Section: Resultsmentioning

confidence: 94%

“…1650 cm −1 (seen in the IR spectra of H 2 L) is shifted to 1545−1556 cm −1 in the spectra of the complexes, suggesting coordination of hydrazidato ligand through the carbonyl oxygen atom. 36 Compounds were further characterized also by NMR spectroscopy (see this section in the Supporting Information).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Geometrically Constrained Molybdenum(VI) Metallosupramolecular Architectures: Conventional Synthesis versus Vapor and Thermally Induced Solid-State Structural Transformations

Vrdoljak

Mandarić

Hrenar

et al. 2019

Crystal Growth & Design

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This contribution describes the synthesis, characterization, and catalytic implementation of the highly constrained molybdenum(VI) polymers [MoO2(LR)] n (with R = H (1), 3OMe (2), and 4OMe (3)) and cyclic tetramer [MoO2(L4OMe)]4 ·0.5MeCN (3′·0.5MeCN) with nicotinoyl hydrazonato ligands (LR) derived from salicylaldehyde (LH), 3-methoxy-2-hydroxybenaldehyde (L3OMe), or 4-methoxy-2-hydroxybenzaldehyde (L4OMe). In order to determine the most stable geometries, conformational analysis of the free and coordinated ligands in these assemblies was carried out through the potential energy surface scans using quantum-chemical methods. The mononuclear analogues [MoO2(HLR)(MeOH)]Cl (R = H (1a) and 3OMe (2a)), [MoO2(HLR)Cl] (R = 3OMe (2b) and 4OMe (3b)), and [MoO2(LR)(MeOH)] (R = H (1c), and 4OMe (3c-α and 3c-β)) were also synthesized and evaluated as potential precursors for reactions in the solid state. Vapor induced transformation of 2a quantitatively afforded complex 2b. The chemometric analysis using principal component analysis was applied to provide insight into the reaction profile. Thermally induced solid-state reactions resulted in the transformation of metallocycle 3′·0.5MeCN and monomeric complexes 1c, 2a, 3c-α, and 3c-β into the corresponding coordination polymers. The structural features responsible for these conversions are discussed in detail. Lastly, the metallosupramolecular architectures were tested as catalysts for cyclooctene epoxidation by using tert-butyl hydroperoxide as an oxidant in water or decane. Compound 3′ is shown to be the most effective and selective catalyst.

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Cobalt(iii) complexes with tridentate hydrazone ligands: protonation state and hydrogen bond competition

Abstract: Differently protonated ligands in [Co(HL)(L)] are stabilized via supramolecular assembling through O–H⋯O/N and N–H⋯N/O hydrogen bonding. Channels spreading either in each space dimension or predominantly in one direction are formed.

Cited by 18 publications

References 67 publications

Chemical fixation of carbon dioxide catalyzed via cobalt (III) ONO pincer ligated complexes

Chemical fixation of carbon dioxide catalyzed via cobalt (III) ONO pincer ligated complexes

Tb₂, Dy₂, and Zn₂Dy₄ Complexes Showing the Unusual Versatility of a Hydrazone Ligand toward Lanthanoid Ions: a Structural and Magnetic Study

Geometrically Constrained Molybdenum(VI) Metallosupramolecular Architectures: Conventional Synthesis versus Vapor and Thermally Induced Solid-State Structural Transformations

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Cobalt(iii) complexes with tridentate hydrazone ligands: protonation state and hydrogen bond competition

Abstract: Differently protonated ligands in [Co(HL)(L)] are stabilized via supramolecular assembling through O–H⋯O/N and N–H⋯N/O hydrogen bonding. Channels spreading either in each space dimension or predominantly in one direction are formed.

Cited by 18 publications

References 67 publications

Chemical fixation of carbon dioxide catalyzed via cobalt (III) ONO pincer ligated complexes

Chemical fixation of carbon dioxide catalyzed via cobalt (III) ONO pincer ligated complexes

Tb2, Dy2, and Zn2Dy4 Complexes Showing the Unusual Versatility of a Hydrazone Ligand toward Lanthanoid Ions: a Structural and Magnetic Study

Geometrically Constrained Molybdenum(VI) Metallosupramolecular Architectures: Conventional Synthesis versus Vapor and Thermally Induced Solid-State Structural Transformations

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Tb₂, Dy₂, and Zn₂Dy₄ Complexes Showing the Unusual Versatility of a Hydrazone Ligand toward Lanthanoid Ions: a Structural and Magnetic Study