Rosario Scopelliti

A metal–organic Au ₁₂ cage was obtained by reaction of a dipyrazole ligand with AuCl(SMe ₂ ).

Reactions of Ph ₂ CCPhM (M = Li or K) with N ₂ O give diazotates, which can be converted with Grignard reagents into azo olefins.

The development of the molecular chemistry of lanthanides in the +4 oxidation state has encountered significant challenges due to their limited solution stability. Here, we demonstrate that combining siloxide ligands with oxo ligands leads to highly stable Pr^IV complexes. We report that the Pr^III/Pr^III oxo-bridged complex, [K(tol)K₄{Pr^III(OSiMe₃)₅}{Pr^III(OSiMe₃)₄}(μ-O)], 4, can be easily prepared by controlled hydrolysis of the pentakis–siloxide complex [K₂Pr^III(OSiMe₃)₅]₂, 2, followed by deprotonation. Oxidation of complex 4 with thianthrene tetrafluoroborate (thiaBF₄) in the presence of KOSiMe₃ afforded the Pr^III/Pr^IV mixed valent complex [K(tol)K₄{Pr^III/IV(OSiMe₃)₅}₂(μ-O)] 5 that showed localized valence with a very short Pr^IV═O bond, consistent with multiple bonding interactions. DFT studies further confirmed the presence of a polarized Pr^IV═O multiple bond along with a very weak ionic Pr^III–O interaction. Further oxidation of complex 5 led to the isolation of the Pr^IV/Pr^IV complex [K₄{Pr^IV(OSiMe₃)₅}₂(μ-O)], 6. Complex 6 shows remarkable solution stability at room temperature over a long period of time. Interestingly, the EPR spectra and magnetic properties of these molecular Pr^IV complexes closely resemble those of Pr^IV ions in perovskite oxide lattices. We anticipate the presented strategy will pave the way for the development of new Ln^IV chemistry.

Dinitrogen cleavage and hydrogenation by metal hydride complexes are relevant to both enzymatic and industrial dinitrogen (N₂) fixation but remain limited to a few examples. Here, we report the cleavage and functionalization of N₂ mediated by a pincer ligand-supported diuranium(IV) hydride complex [{(Dipp-NON)U^IV(η⁴-HDipp)}(μ-H){(η⁶-Dipp)U^IV(NON-Dipp)}], 1. In this complex, a total of six electrons and two protons are stored in two flanking arms of the bis(anilido)xanthene scaffolds and in the bridging hydride, which are stabilized by two uranium(IV) centers. The reaction of complex 1 with dinitrogen results in concomitant N₂ cleavage and functionalization, affording the bis-imido complex [{(Dipp₂-NON)U^IV}₂(μ-NH)₂], 3, via an unprecedented cooperative metal–ligand pathway and without involving a change of the uranium oxidation state during the overall transformation.

Diazoolefins can be functionalized by postsynthetic modification via backbone metallation.

Substituting a nitrogen for a chalcogen in N-heterocyclic carbenes alters the electronic and steric features of the resulting metal complexes, influencing their biological activity and creating new opportunities for metallocarbene drug candidates.

Anionic Ln( iv ) complexes were synthesised by tuning the reaction condition, demonstrating the possibility of accessing charged Pr( iv ) complexes as a tool to manipulate the redox potential and therefore lead to more stable complexes.

Exchange reactions between Au₃(pyrazolate)₃ trimers and ‘free’ pyrazole ligands are slow, and they can display pronounced autocatalytic behavior.

The well-defined catalytic conversion of dinitrogen (N₂) to ammonia (NH₃) by molecular complexes is of fundamental interest and important for providing an atomic-level understanding of reactivity that can be related to industrial and biological nitrogen-fixation processes. Molecular catalytic N₂ to NH₃ conversion currently involves the reduction and protonation of terminal or bridging end-on bound metal–N₂ complexes. However, catalytic N₂ to NH₃ conversion by side-on bound metal–N₂ molecular complexes is relevant to both the industrial and biological nitrogen-fixation processes. Here, using a uranium triamidoamine complex, we report catalytic N₂ to NH₃ conversion involving side-on bound N₂ binding. Stoichiometric reactions reveal stepwise reduction of N₂ from free N₂ to bridging side-on bound forms and subsequently to bridging nitrides, uniquely accessing four different states of side-on bound N₂ for the same molecular system. This reveals the roles of N₂, N₂ ²⁻, N₂ ³⁻, N₂ ⁴⁻ and N³⁻ in the catalytic conversion of N₂ to NH₃ when involving side-on bridging N₂.