Systematic comparison of the structure of homoleptic tetradentate N2O2-type Schiff base complexes of tetravalent f-elements (M(<scp>iv</scp>) = Ce, Th, U, Np, and Pu) in solid state and in solution

Radoske, Thomas; Kloditz, Roger; Fichter, Sebastian; März, Juliane; Patzschke, Michael; Schmidt, Moritz; Stumpf, Thorsten; Walter, Olaf; Ikeda‐Ohno, Atsushi

doi:10.1039/d0dt03405c

Cited by 16 publications

(13 citation statements)

References 68 publications

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“…Spin–orbit coupling (SOC) has only a minor effect on structures, even for actinides. This was recently even shown for a similar ligand system . Therefore, SOC effects were neglected throughout the study.…”

Section: Methodsmentioning

confidence: 71%

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)₂]

et al. 2021

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Key questions for the study of chemical bonding in actinide compounds are the degree of covalency that can be realized in the bonds to different donor atoms and the relative participation of 5f and 6d orbitals. A manifold of theoretical approaches is available to address these questions, but hitherto no comprehensive assessments are available. Here, we present an in-depth analysis of the metal–ligand bond in a series of actinide metal–organic compounds of the [M(salen)2] type (M = Ce, Th, Pa, U, Np, Pu) with the Schiff base N,N′-bis(salicylidene)ethylenediamine (salen). All compounds except the Pa complex (only included in the calculations) have been synthesized and characterized experimentally. The experimental data are then used as a basis to quantify the covalency of bonds to both N- and O-donor atoms using simple electron-density differences and the quantum theory of atoms in molecules (QTAIM) with interacting quantum atoms. In addition, the orbital origin of any covalent contributions was studied via natural population analysis (NPA). The results clearly show that the bond to the hard, charged O-donor atoms of salen is consistently not only stronger but also more covalent than bonds to the softer N-donor atoms. On the other hand, in a comparison of the metals, Th shows the most ionic bond character even compared to its 4f analogue Ce. A maximum of the covalency is found for Pa or Np by their absolute and relative covalent bond energies, respectively. This trend also correlates with a significant f- and d-orbital occupation for Pa and Np. These results underline that only a comprehensive computational approach is capable of fully characterizing the covalency in actinide complexes.

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Section: Methodsmentioning

confidence: 71%

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)₂]

et al. 2021

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“…They are used in extracting many metallic ions from water due to their ability to form stable metal chelates complexes. They are widely studied in coordination chemistry, especially those which contains heterocyclic compounds with the azomethene group, as it has basic properties due to the presence of an electron pair on the nitrogen atom azomethene (-C=N) and often pentagonal or hexagonal rings with the metal ion [1][2][3]. Heavy metal pollutions are released into the environment by industrial activities affecting the ecosystem.…”

Section: ■ Introductionmentioning

confidence: 99%

Preparation and Characterization of New Tetra-Dentate N2O2 Schiff Base with Some of Metal Ions Complexes

2021

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This study describes preparation a new series of tetra-dentate N2O2 dinuclear complexes Cr(III), Co(II)and Cu(II) of the Schiff base 2-[5-(2-hydroxy-phenyl)-1,3,4-thiadiazol-2-ylimino]-methyl-naphthalen-1-ol], (LH2) derived from 1-hydroxy-naphthalene-2-carbaldehyde with 2-amino-5-(2-hydroxy-phenyl)-1,3,4-thiadiazole. These ligands were characterized by FT-IR, UV-Vis, Mass spectra, elemental analysis, and 1H-NMR. All prepared complexes have been characterized by conductance measurement, magnetic susceptibility, electronic spectra, infrared spectrum, thermal Analysis (TGA), and metal analysis by atomic absorption. The stoichiometry of metal to ligand, magnetic susceptibility, and electronic spectra measurements show an octahedral geometry for all (Cr3+, Co2+, Cu2+) complexes. Conductivity measurement shows that the prepared (Co2+, Cu2+) complexes were nonelectrolyte except (Cr3+). Studying the extraction efficiency such as ligand concentration, temperature and incubation time, centrifuge time, amount of surfactant were evaluated and optimized. The linear range of ions Cr(III), Co(II) and Cu(II) with ligand (0.2–3, 0.2–4, 0.2–3, µg mL–1), each individually, and relative standard deviation (0.15%, 0.34%, 0.46%). The successful method was applied for the determination of trace metal ions in the wastewater.

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“…However, in the salen system An bonding was dominated by the strong, hard O ‐donor, which ultimately limits the flexibility of the An−N bond to react to changes in electronic situation, for example, caused by backbonding. Studies of pure N donors remain scarce, especially for the transuranium elements [8–11] . To the best of our knowledge, only two Pu IV complexes exclusively stabilised by N ‐donor ligands are known in the literature: One containing the inorganic NCS − ligands [12] and one with a TREN (tris(2‐aminoethyl)amine)‐type ligand [13] …”

Section: Introductionmentioning

confidence: 99%

“…Studies of pure N donors remain scarce, especially for the transuranium elements. [8][9][10][11] To the best of our knowledge, only two Pu IV complexes exclusively stabilised by N-donor ligands are known in the literature: One containing the inorganic NCS À ligands [12] and one with a TREN (tris(2-aminoethyl)amine)-type ligand. [13] To address the question of AnÀ N (back)bonding in metalorganic actinide compounds and expand the structural database of transuranium element complexes, we here study the actinide complex series of the pure N-donor ligand N,N'ethylene-bis((pyrrole-2-yl)methanimine (H 2 pyren, H 2 L, which is structurally closely related to salen.…”

Section: Introductionmentioning

confidence: 99%

How 5 f Electron Polarisability Drives Covalency and Selectivity in Actinide N‐Donor Complexes

Köhler

Patzschke

Schmidt

et al. 2021

Chemistry A European J

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We report a series of isostructural tetravalent actinide (Th, U−Pu) complexes with the N‐donor ligand N,N’‐ethylene‐bis((pyrrole‐2‐yl)methanimine) (H2L, H2pyren). Structural data from SC‐XRD analysis reveal [An(pyren)2] complexes with different An−Nimine versus An−Npyrrolide bond lengths. Quantum chemical calculations elucidated the bonding situation, including differences in the covalent character of the coordinative bonds. A comparison to the intensely studied analogous N,N′‐ethylene‐bis(salicylideneimine) (H2salen)‐based complexes [An(salen)2] displays, on average, almost equal electron sharing of pyren or salen with the AnIV, pointing to a potential ligand‐cage‐driven complex stabilisation. This is shown in the fixed ligand arrangement of pyren and salen in the respective AnIV complexes. The overall bond strength of the pure N‐donor ligand pyren to AnIV (An=Th, U, Np, Pu) is slightly weaker than to salen, with the exception of the PaIV complex, which exhibits extraordinarily high electron sharing of pyren with PaIV. Such an altered ligand preference within the early AnIV series points to a specificity of the 5f1 configuration, which can be explained by polarisation effects of the 5 f electrons, allowing the strongest f electron backbonding from PaIV (5f1) to the N donors of pyren.

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Systematic comparison of the structure of homoleptic tetradentate N₂O₂-type Schiff base complexes of tetravalent f-elements (M(iv) = Ce, Th, U, Np, and Pu) in solid state and in solution

Abstract: Tetradentate N2O2-type Schiff base complexes with tetravalent 4f- and 5f-block metals, [M(salpn)2] (H2salpn = N,N′-disalicylidene-1,3-diaminopropane; M = Ce, Th, U, Np, and Pu), were characterised both in the solid state and in solution.

Cited by 16 publications

References 68 publications

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)₂]

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)₂]

Preparation and Characterization of New Tetra-Dentate N<sub>2</sub>O<sub>2</sub> Schiff Base with Some of Metal Ions Complexes

How 5 f Electron Polarisability Drives Covalency and Selectivity in Actinide N‐Donor Complexes

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Systematic comparison of the structure of homoleptic tetradentate N2O2-type Schiff base complexes of tetravalent f-elements (M(iv) = Ce, Th, U, Np, and Pu) in solid state and in solution

Abstract: Tetradentate N2O2-type Schiff base complexes with tetravalent 4f- and 5f-block metals, [M(salpn)2] (H2salpn = N,N′-disalicylidene-1,3-diaminopropane; M = Ce, Th, U, Np, and Pu), were characterised both in the solid state and in solution.

Cited by 16 publications

References 68 publications

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)2]

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)2]

Preparation and Characterization of New Tetra-Dentate N<sub>2</sub>O<sub>2</sub> Schiff Base with Some of Metal Ions Complexes

How 5 f Electron Polarisability Drives Covalency and Selectivity in Actinide N‐Donor Complexes

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Systematic comparison of the structure of homoleptic tetradentate N₂O₂-type Schiff base complexes of tetravalent f-elements (M(iv) = Ce, Th, U, Np, and Pu) in solid state and in solution

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)₂]

Comprehensive Bonding Analysis of Tetravalent f-Element Complexes of the Type [M(salen)₂]