Rosario Scopelliti

A Route to Stabilize Uranium(II) and Uranium(I) Synthons in Multimetallic Complexes

Marinella Mazzanti, Rosario Scopelliti, Ivica Zivkovic

Herein, we report the redox reactivity of a multimetallic uranium complex supported by triphenylsiloxide (−OSiPh3) ligands, where we show that low valent synthons can be stabilized via an unprecedented mechanism involving intramolecular ligand migration. The two- and three-electron reduction of the oxo-bridged diuranium(IV) complex [{(Ph3SiO)3(DME)U}2(μ-O)], 4, yields the formal “UII/UIV”, 5, and “UI/UIV”, 6, complexes via ligand migration and formation of uranium-arene δ-bond interactions. Remarkably, complex 5 effects the two-electron reductive coupling of pyridine affording complex 7, which demonstrates that the electron-transfer is accompanied by ligand migration, restoring the original ligand arrangement found in 4. This work provides a new method for controlling the redox reactivity in molecular complexes of unstable, low-valent metal centers, and can lead to the further development of f-elements redox reactivity.

2023

Head‐to‐Tail Dimerization of N‐Heterocyclic Diazoolefins

Zhaowen Dong, Farzaneh Fadaei Tirani, Wolfram Feuerstein, Anastasia Gitlina, Rosario Scopelliti, Kay Severin, Andrzej Sienkiewicz, Paul Varava

The head-to-tail dimerization of N-heterocyclic diazoolefins is described. The products of these formal (3+3) cycloaddition reactions are strongly reducing quinoidal tetrazines. Oxidation of the tetrazines occurs in a stepwise fashion, and we were able to isolate a stable radical cation and diamagnetic dications. The latter are also accessible by oxidative dimerization of diazoolefins.

2023

Synthesis and Reactivity of an Anionic Diazoolefin

Zhaowen Dong, Farzaneh Fadaei Tirani, Bastiaan Kooij, Rosario Scopelliti, Kay Severin

Bent (hetero)allenes such as carbodicarbenes and carbodiphosphoranes can act as neutral C-donor ligands, and diverse applications in coordination chemistry have been reported. N-Heterocyclic diazoolefins are heterocumulenes, which can function in a similar fashion as L-type ligands. Herein, we describe the synthesis and the reactivity of an anionic diazoolefin. This compound displays distinct reactivity compared to neutral diazoolefins, as evidenced by the preparation of diazo compounds via protonation, alkylation, or silylation. The anionic diazoolefin can be employed as an ambidentate, X-type ligand in salt metathesis reactions with metal halide complexes. Extrusion of dinitrogen was observed in a reaction with PCl(NiPr2)2, resulting in a stable phosphinocarbene.

2023

A Mesoionic Diselenolene Anion and the Corresponding Radical Dianion

Cesare Berton, Zhaowen Dong, Farzaneh Fadaei Tirani, Rosario Scopelliti, Kay Severin, Andrzej Sienkiewicz, Abdusalom Suleymanov

Dichalcogenolenes are archetypal redox non-innocent ligands with numerous applications. Herein, we describe a diselenolene ligand with fundamentally different electronic properties. By selenation of a C2-protected imidazolium salt, we have prepared a mesoionic diselenolene. This ligand is diamagnetic, which is in contrast to the paramagnetic nature of standard dichalcogenolene monoanions. The new ligand is also redox-active, as demonstrated by isolation of a stable diselenolene radical dianion. The unique electronic properties of the new ligand give rise to unusual coordination chemistry. Thus, we were able to prepare a hexa-coordinate aluminum tris(diselenolene) complex, and a Lewis acidic aluminate complex with two ligand-centered unpaired electrons.

2022

Copper Complexes with Diazoolefin Ligands and their Photochemical Conversion into Alkenylidene Complexes

Farzaneh Fadaei Tirani, Bastiaan Kooij, Rosario Scopelliti, Kay Severin, Paul Varava

Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of Cu(I) complexes with N-heterocyclic diazoolefins ligands. The complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature.

2022

Fluorinated Tetraarylethenes: Universal Tags for the Synthesis of Solid State Luminogens

Thibault Jacques Marie Damiens Vanrapenbusch, Farzaneh Fadaei Tirani, Barbara Maja Kraus, Albert Ruggi, Rosario Scopelliti, Kay Severin, Euro Solari, Abdusalom Suleymanov

The aggregation-induced emission properties of tetraarylethenes (TAEs) have led to numerous applications in chemistry, biology, and materials science. Herein, we describe two fluorinated tetraarylethenes, which can be employed as universal tags for the synthesis of solid state luminogens. The tags are accessible in one or two steps from commercially available starting materials. Facile coupling reactions with ubiquitous substrates such as thiols, alcohols, amines, phosphines, aldehydes, and enamines allow preparing a wide range of TAE conjugates, including tagged amino acids, peptides, carbohydrates, steroids, and commercial polymers.

2022

Heterometallic uranium/molybdenum nitride synthesis via partial N-atom transfer

Luciano Barluzzi, Nadir Jori, Marinella Mazzanti, Rosario Scopelliti

The reaction of a terminal Mo(II) nitride with a U(III) complex yields an heterodimetallic U-Mo nitride which is the first example of a transition metal-capped uranium nitride. The nitride is triply bonded to U(V) and singly bonded to Mo(0) and supports a U-Mo interaction. This compound shows reactivity toward CO oxidation.

2022

LiBF4‐Induced Rearrangement and Desymmetrization of a Palladium‐Ligand Assembly

Farzaneh Fadaei Tirani, Rosario Scopelliti, Kay Severin, Sylvain Alexandre Marie Sudan

Thirteen palladium-ligand assemblies with different structures and topologies were investigated for the ability to bind lithium ions. In one case, the addition of LiBF4 resulted in a profound structural rearrangement, converting a dincluclear [Pd2L4]2 complex into a low-symmetry [Pd4L8]8+ assembly with two binding pockets for solvated LiBF4 ion pairs. The rearrangement could only be induced by Li+, indicating highly specific host-guest interaction. A structural analysis of the [Pd4L8]8+ receptor revealed a compact structure with multiple intramolecular interactions, reminiscent of what is seen for natural and synthetic foldamers.

2022

Reactivity of Multimetallic Thorium Nitrides Generated by Reduction of Thorium Azides

Luciano Barluzzi, Fang-Che Hsueh, Marinella Mazzanti, Rosario Scopelliti

Thorium nitrides are likely intermediates in the reported cleavage and functionalization of dinitrogen by molecular thorium complexes and are attractive compounds for the study of multiple bond formation in f-element chemistry, but only one example of thorium nitride isolable from solution was reported. Here, we show that stable multimetallic azide/nitride thorium complexes can be generated by reduction of thorium azide precursors─a route that has failed so far to produce Th nitrides. Once isolated, the thorium azide/nitride clusters, M3Th═N═Th (M = K or Cs), are stable in solutions probably due to the presence of alkali ions capping the nitride, but their synthesis requires a careful control of the reaction conditions (solvent, temperature, nature of precursor, and alkali ion). The nature of the cation plays an important role in generating a nitride product and results in large structural differences with a bent Th═N═Th moiety found in the K-bound nitride as a result of a strong K–nitride interaction and a linear arrangement in the Cs-bound nitride. Reactivity studies demonstrated the ability of Th nitrides to cleave CO in ambient conditions yielding CN–.

2022