Bonding and Reactivity in Terminal versus Bridging Arenide Complexes of Thorium Acting as Th^II Synthons

Abstract

Thorium redox chemistry is extremely scarce due to the high stability of ThIV. Here we report two unique examples of thorium arenide complexes prepared by reduction of a ThIV‐siloxide complex in presence of naphthalene, the mononuclear arenide complex [K(OSi(OtBu)3)3Th(η6‐C10H8)] (1) and the inverse‐sandwich complex [K(OSi(OtBu)3)3Th]2(μ‐η6,η6‐C10H8)] (2). The electrons stored in these complexes allow the reduction of a broad range of substrates (N2O, AdN3, CO2, HBBN). Higher reactivity was found for the complex 1 which reacts with the diazoolefin IDipp=CN2 to yield the unexpected ThIV amidoalkynyl complex 5 via a terminal N‐heterocyclic vinylidene intermediate. This work showed that arenides can act as convenient redox‐active ligands for implementing thorium‐ligand cooperative multielectron transfer and that the reactivity can be tuned by the arenide binding mode.

Diazoalkenes: From an Elusive Intermediate to a Stable Substance Class in Organic Chemistry

“…Upon reaction of diazoalkene 44 A with the thorium arene precursor 91 the Th IV amido acetylido complex 92 could be isolated (Scheme 24). [76] …”

“…Upon reaction of diazoalkene 44 A with the thorium arene precursor 91 the Th IV amido acetylido complex 92 could be isolated (Scheme 24). [76] The unusual cleavage of the imidazole heterocyclic backbone was computationally investigated and is likely to be a result of the reduction of the diazoalkene by the Thprecursor. A Th-vinylidene intermediate is computationally proposed as transient intermediate, but could not be spectroscopically identified.…”

Diazoalkene – Von einem flüchtigen Intermediat zu einer neuen stabilen Substanzklasse in der Organischen Chemie

“…Bei der Reaktion von Diazoalken 44 A mit dem Thoriumaren‐Vorläufer 91 konnte der Th IV ‐Amido‐Acetylido‐Komplex 92 isoliert werden (Schema 24). [76] …”

“…Bei der Reaktion von Diazoalken 44 A mit dem Thoriumaren-Vorläufer 91 konnte der Th IV -Amido-Acetylido-Komplex 92 isoliert werden (Schema 24). [76] Die ungewöhnliche Spaltung des heterocyclischen Imidazol-Rückgrats wurde rechnerisch untersucht und ist wahrscheinlich auf die Reduktion des Diazoalkens durch den Th-Vorläufer zurückzuführen. Ein Th-Vinylidenzwischenprodukt wird rechnerisch als reaktives Intermediat vorgeschlagen, konnte aber spektroskopisch nicht identifiziert werden.…”

Topology-Dependent Synthesis, Structures, and Bonding Interactions of Uranium Polyarene Complexes

“…Main group and transition metal polyarene complexes have been studied for a variety of polyarenes with different degrees of reduction and coordination modes (Figure b), ,,− together with reactivity , and electronic properties . Albeit rarer, rare-earth metal complexes of reduced anthracene, pyrene, and tetracene anions have been reported. − In contrast, while uranium is prone to form inverse-sandwich structures with benzene and substituted benzenes, featuring δ bonding interactions, − actinide polyarene complexes are scarce and mostly limited to naphthalene. ,− Only recently, Fortier and co-workers reported the synthesis of π-bound uranium anthracene complexes (Figure c). , The lack of uranium polyarene complexes and their potential applications in synthesis and material sciences prompted us to explore the possible formation of uranium polyarene complexes with a variety of polyarenes. Herein, we report the synthesis and characterization of a series of uranium polyarene complexes, with the number of fused rings ranging from three to five.…”