Differences in actinide metal–ligand orbital interactions: comparison of U(iv) and Pu(iv) β-ketoiminate N,O donor complexes

The quest for simple ligands to participate in concerted base metal-ligand multiple-electron redox events is driven by perspectives of replacing noble metals in catalysis and for discovering novel chemical reactivity. Yet the vast majority of simple ligand systems displays electrochemical potentials impractical for catalytic cycles substantiating the importance of new strategies towards aligned metal–ligand orbital energy levels. We herein demonstrate the possibility to establish and tame the elusive non-innocence of the ubiquitous acetylacetonate (acac), that is the most commonly employed anionic, chelating ligand towards elements across the entire Periodic Table. By employing the ligand field in the high-spin Cr(II) as a thermodynamic switch, we were able to chemically tailor the occurrence of metal–ligand redox events. The very mechanism can be understood as a destabilization of the dz2 orbital relative to the pi* LUMO of acac, which proffers a generalizable strategy to synthetically engineer non-innocence with seemingly redox-inactive ligands.

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Syntheses, spectroscopic, redox, and structural properties of homoleptic Iron(III/II) dithione complexes

RSC Advances ◽

10.1039/d0ra07371g ◽

2020 ◽

Vol 10 (63) ◽

pp. 38294-38303

Author(s):

Kyle J. Colston ◽

Sara A. Dille ◽

Benjamin Mogesa ◽

Jacilynn Brant ◽

Victor N. Nemykin ◽

...

Keyword(s):

Structural Properties ◽

Ligand Orbital ◽

Orbital Mixing ◽

Metal Ligand

Two sets of FeIII/II complexes, synthesized from N,N′-diisopropyl piperazine-2,3-dithione (iPr2Dt0) and N,N′-dimethyl piperazine-2,3-dithione (Me2Dt0) ligands, exhibit electronically asymmetrical ligands with metal–ligand orbital mixing.

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Metal−Metal Bonding in Rh2(O2CCF3)4: Extensive Metal−Ligand Orbital Mixing Promoted by Filled Fluorine Orbitals

Journal of the American Chemical Society ◽

10.1021/ja993618l ◽

2000 ◽

Vol 122 (13) ◽

pp. 3182-3190 ◽

Cited By ~ 14

Author(s):

Dennis L. Lichtenberger ◽

John R. Pollard ◽

Matthew A. Lynn ◽

F. A. Cotton ◽

Xuejun Feng

Keyword(s):

Metal Bonding ◽

Metal Metal ◽

Ligand Orbital ◽

Orbital Mixing ◽

Metal Ligand

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Mechanistic Insights into Co and Fe Quaterpyridine-Based CO2 Reduction Catalysts: Metal–Ligand Orbital Interaction as the Key Driving Force for Distinct Pathways

Journal of the American Chemical Society ◽

10.1021/jacs.0c09380 ◽

2021 ◽

Author(s):

Matthias Loipersberger ◽

Delmar G. A. Cabral ◽

Daniel B. K. Chu ◽

Martin Head-Gordon

Keyword(s):

Driving Force ◽

Co2 Reduction ◽

Orbital Interaction ◽

Ligand Orbital ◽

Reduction Catalysts ◽

Metal Ligand

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Ligand Field-Actuated Non-Innocence of Acetylacetonate

10.26434/chemrxiv.12052884.v1 ◽

2020 ◽

Author(s):

Morten Gotthold Vinum ◽

Laura Voigt ◽

Steen Hansen ◽

Colby Bell ◽

Kensha Marie Clark ◽

...

Keyword(s):

Noble Metals ◽

Chemical Reactivity ◽

Energy Levels ◽

Orbital Energy ◽

Ligand Field ◽

Ligand Orbital ◽

Catalytic Cycles ◽

Electrochemical Potentials ◽

New Strategies ◽

Metal Ligand

The quest for simple ligands to participate in concerted base metal-ligand multiple-electron redox events is driven by perspectives of replacing noble metals in catalysis and for discovering novel chemical reactivity. Yet the vast majority of simple ligand systems displays electrochemical potentials impractical for catalytic cycles substantiating the importance of new strategies towards aligned metal–ligand orbital energy levels. We herein demonstrate the possibility to establish and tame the elusive non-innocence of the ubiquitous acetylacetonate (acac), that is the most commonly employed anionic, chelating ligand towards elements across the entire Periodic Table. By employing the ligand field in the high-spin Cr(II) as a thermodynamic switch, we were able to chemically tailor the occurrence of metal–ligand redox events. The very mechanism can be understood as a destabilization of the dz2 orbital relative to the pi* LUMO of acac, which proffers a generalizable strategy to synthetically engineer non-innocence with seemingly redox-inactive ligands.

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An Estimation Method of Metal-Ligand Orbital Mixing in Lanthanide(III) Complexes Using Magnetic Circular Dichroism

ChemistrySelect ◽

10.1002/slct.201800050 ◽

2018 ◽

Vol 3 (9) ◽

pp. 2646-2648 ◽

Cited By ~ 1

Author(s):

Yuichi Kitagawa ◽

Takayuki Nakanishi ◽

Koji Fushimi ◽

Yasuchika Hasegawa

Keyword(s):

Circular Dichroism ◽

Magnetic Circular Dichroism ◽

Estimation Method ◽

Ligand Orbital ◽

Orbital Mixing ◽

Circular Dichroïsm ◽

Metal Ligand

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Synthesis and Luminescence Properties of [Pt{4-(o-MeC6H4)- pzbipy}Cl]SbF6 [pzbipy = 6-2''-pyrazinyl)-2,22'-bipyridine]

Zeitschrift für Naturforschung B ◽

10.1515/znb-2007-0319 ◽

2007 ◽

Vol 62 (3) ◽

pp. 447-452 ◽

Cited By ~ 4

Author(s):

John S. Field ◽

Jan-André Gertenbach ◽

Raymond J. Haines ◽

Orde Q. Munro ◽

David R. McMillin

Keyword(s):

Excited State ◽

Charge Transfer ◽

Variable Temperature ◽

Emission Spectra ◽

Fluid Solution ◽

Orbital Interactions ◽

Low Intensity ◽

Ligand Charge Transfer ◽

Metal Metal ◽

Metal Ligand

The synthesis and characterisation of the 4-(o-R-C6H4)pzbipy [R = H, CH3 or CF3; pzbipy = 6-(2″- pyrazinyl)-2,2′-bipyridyl] ligands are described. Reaction of the 4-(o-MeC6H4)pzbipy ligand with [Pt(PhCN)2Cl2] in the presence of AgSbF6 affords [Pt{4-(o-MeC6H4)pzbipy}Cl]SbF6 as a marooncoloured microcrystalline solid. The [Pt{4-(o-MeC6H4)pzbipy}Cl]+ cation exhibits low intensity photoluminescence in dichloromethane that maximises at 543 nm and which is assigned to a 3MLCT excited state (τ = 20 ns). The emission spectrum of the cation was also recorded in a frozen DME {1 : 5:5 (v/v) DMF / MeOH / EtOH} glass; a highly structured band is observed with vibrational spacings of ca. 1400 cm−1, indicating emission from an intraligand 3π-π∗ state (τ = 11 μs). Variable temperature solid emission spectra show maxima that occur at significantly lower energies than is observed in fluid solution and that shift to the red when the temperature is lowered; specifically, λ (em)max is 674 nm at 280 K (τ = 80 ns) and 723 nm at 80 K (τ = 1.3 μs). Emission behaviour of this type is typical of emission from a metal-metal-ligand charge transfer (MMLCT) excited state that has its origins in dz² (Pt)-dz² (Pt) orbital interactions in the crystal.

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