Multielectron Redox Chemistry of Ytterbium Complexes Reaching the +1 and Zero Formal Oxidation States.

Lanthanide redox reactivity remains limited to one-electron transfer reactions due to their inability to access a broad range of oxidation states. Here, we show that multielectron reductive chemistry is achieved for ytterbium by using the tripodal tris(siloxide)arene redox-active ligand, which can store two electrons in the arene anchor. Reduction of the Yb(III) complex of the tris(siloxide)arene tripodal ligand affords the Yb(II) analogue by metal-centered reduction.

The photo-isomerization of the cyclononatetraenyl ligand and related rare earth complexes.

The cyclononatetraenyl (Cnt) ligand is a large monoanionic ligand. It is easily synthesized by ring expansion after cyclopropanation of the cyclooctatetraenyl (Cot) ligand. The Cnt ligand can be reported as the --- () isomer, where the aromatic ring is flat, and all carbon atoms form a homogenous ring, and as the --- () isomer, where one carbon places itself inside the ring.

Preparation and Ground-State Electronic Structure of Heterobimetallic Yb-Pt-Alkyl Complexes.

This article focuses on the synthesis of heterobimetallic complexes of lanthanide and platinum. It describes the synthesis of the Cp*Yb(bipym)PtMe complex and its characterization, followed by its reactivity with oxidants, giving access to various Pt + IV compounds of trismethyl (PtMe) and tetramethyl (PtMe) fragments. Characterization of the electronic properties of the complexes by magnetic measurements demonstrated that the tetramethyl complex possesses a singlet ground state.

Siloxide tripodal ligands as a scaffold for stabilizing lanthanides in the +4 oxidation state.

Synthetic strategies to isolate molecular complexes of lanthanides, other than cerium, in the +4 oxidation state remain elusive, with only four complexes of Tb(iv) isolated so far. Herein, we present a new approach for the stabilization of Tb(iv) using a siloxide tripodal trianionic ligand, which allows the control of unwanted ligand rearrangements, while tuning the Ln(iii)/Ln(iv) redox-couple. The Ln(iii) complexes, [Ln((OSiPhAr)-arene)(THF)] (1-Ln) and [K(toluene){Ln((OSiPhAr)-arene)(OSiPh)}] (2-Ln) (Ln = Ce, Tb, Pr), of the (HOSiPhAr)-arene ligand were prepared.

A trinuclear metallasilsesquioxane of uranium(III).

The silsesquioxane ligand (Bu)SiO(OH) (POSSH) is revealed as an attractive system for the assembly of robust polynuclear complexes of uranium(III) and allowed the isolation of the first example of a trinuclear U(III) complex ([U(POSS)]) that exhibits magnetic communication and promotes dinitrogen reduction in the presence of reducing agent.

Multielectron Redox Chemistry of Uranium by Accessing the +II Oxidation State and Enabling Reduction to a U(I) Synthon.

The synthesis of molecular uranium complexes in oxidation states lower than +3 remains a challenge despite the interest for their multielectron transfer reactivity and electronic structures. Herein, we report the one- and two-electron reduction of a U(III) complex supported by an arene-tethered tris(siloxide) tripodal ligand leading to the mono-reduced complexes, [K(THF)U((OSi(OBu)Ar)-arene)(THF)] () and [K(2.2.

Correction to "Electron Shuttle in -Heteroaromatic Ni Catalysts for Alkene Isomerization".

[This corrects the article DOI: 10.1021/jacsau.2c00251.

Electron Shuttle in -Heteroaromatic Ni Catalysts for Alkene Isomerization.

Simple -heteroaromatic Ni(II) precatalysts, (L)NiMe (L = bipy, bipym), were used for alkene isomerization. With an original reduction method using a simple borane (HB(Cat)), a low-valent Ni center was formed readily and showed good conversion when a reducing divalent lanthanide fragment, Cp*Yb, was coordinated to the (bipym)NiMe complex, a performance not achieved by the monometallic (bipy)NiMe analogue. Experimental mechanistic investigations and computational studies revealed that the redox non-innocence of the L ligand triggered an electron shuttle process, allowing the elusive formation of Ni(I) species that were central to the isomerization process.

Size-Controlled Hapticity Switching in [Ln(C H )(C H )] Sandwiches.

Sandwich complexes of lanthanides have recently attracted a considerable amount of interest due to their applications as Single Molecule Magnet (SMM). Herein, a comprehensive series of heteroleptic lanthanide sandwich complexes ligated by the cyclononatetraenyl (Cnt) and the cyclooctatetraenyl (Cot) ligand [Ln(Cot)(Cnt)] (Ln=Tb, Dy, Er, Ho, Yb, and Lu) is reported. The coordination behavior of the Cnt ligand has been investigated along the series and shows different coordination patterns in the solid-state depending on the size of the corresponding lanthanide ion without altering its overall anisotropy.

Bis-cyclooctatetraenyl Thulium(II): Highly Reducing Lanthanide Sandwich Single Molecule Magnets.

Divalent lanthanide organometallics are well-known highly reducing compounds usually used for single electron transfer reactivity and small molecule activation. Thus, their very reactive nature prevented for many years the study of their physical properties, such as magnetic studies on a reliable basis. In this article, the access to rare organometallic sandwich compounds of Tm with the cyclooctatetraenyl (Cot) ligand impacts on the use of divalent organolanthanide compounds as an additional strategy for the design of performing Single Molecule Magnets (SMM).

Redox activity of a dissymmetric ligand bridging divalent ytter-bium and reactive nickel fragments.

The reaction of a reactive nickel dimethyl bearing a redox-active, dissymmetric ligand, which is obtained by deprotonation of 2-pyrimidin-2-yl-1H-benzimidazole (Hbimpm) with a divalent lanthanide complex, Cp*Yb(OEt), affords an unprecedented, trimeric with C(sp)-C(sp) bond formation between two ligands in an exo position. Meanwhile, the transient, dimeric species can be isolated with the same ligand coupling fashion, however, with a drastic distorsion angle of the bimpm ligand and reactive NiMe fragment, revealing the possible mechanism of this rearrangement. A much more stable dimeric congener, , with an exo ligand coupling, is synthesized in the presence of 18-crown-6, which captures the potassium counter ion.

Intermediate Valence States in Lanthanide Compounds.

Over more than 50 years, intermediate valence states in lanthanide compounds have often resulted in unexpected or puzzling spectroscopic and magnetic properties. Such experimental singularities could not be rationalised until new theoretical models involving multiconfigurational electronic ground states were established. In this minireview, the different singularities that have been observed among lanthanide complexes are highlighted, the models used to rationalise them are detailed and how such electronic effects may be adjusted depending on energy and symmetry considerations is considered.

Reversible electron transfer in organolanthanide chemistry.

This article relates the synthesis and characterization of novel heterobimetallic complexes containing a low-valent lanthanide, a tetradentate redox non-innocent ligand, the 4,5,9,10-tetraazaphenanthrene, taphen ligand and transition metal fragments of PdMe and PtMe. The experimental results are supported by a theoretical study. Investigation of their reduction properties allowed the formation of isostructural original heterotrimetallic complexes containing two Cp*Yb fragments and the (taphen)MMe (M = Pd and Pt) motifs.

Reactive Heterobimetallic Complex Combining Divalent Ytterbium and Dimethyl Nickel Fragments.

This article presented the synthesis and characterization of original heterobimetallic species combining a divalent lanthanide fragment and a divalent nickel center bridged by the bipyrimidine ligand, a redox-active ligand. X-ray crystal structures were obtained for the Ni monomer (bipym)NiMe, , as well as the heterobimetallic dimer compounds, Cp*Yb(bipym)NiMe, , along with H solution NMR, solid-state magnetic data, and DFT calculations only for . The reactivity with CO was investigated on both compounds and the stoichiometric acetone formation is discussed based on kinetic and mechanistic studies.

Magnetism and variable temperature and pressure crystal structures of a linear oligonuclear cobalt bis-semiquinonate.

The crystal structure of the first oligomeric cobalt dioxolene complex, Co3(3,5-DBSQ)2((t)BuCOO)4(NEt3)2, 1, where DBSQ is 3,5-di-tert-butyl-semiquinonate, has been studied at various temperatures between 20 and 200 K. Despite cobalt-dioxolene complexes being generally known for their extensive ability to exhibit valence tautomerism (VT), we show here that the molecular geometry of compound 1 is essentially unchanged over the full temperature range, indicating the complete absence of electron transfer between ligand and metal. Magnetic susceptibility measurements clearly support the lack of VT between 8 and 300 K.