Sara Sabater

Bromide abstraction from the three-coordinate Ni(I) ring-expanded N-heterocyclic carbene complex [Ni(6-Mes)(PPh₃)Br] (1; 6-Mes = 1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) with TlPF₆ in THF yields the T-shaped cationic solvent complex, [Ni(6-Mes)(PPh₃)(THF)][PF₆] (2), whereas treatment with NaBAr^F ₄ in Et₂O affords the dimeric Ni(I) product, [{Ni(6-Mes)(PPh₃)}₂(μ-Br)][BAr^F ₄] (3). Both 2 and 3 act as latent sources of the cation [Ni(6-Mes)(PPh₃)]⁺, which can be trapped by CO to give [Ni(6-Mes)(PPh₃)(CO)]⁺ (5). Addition of [(Et₃Si)₂(μ-H)][B(C₆F₅)₄] to 1 followed by work up in toluene results in the elimination of phosphine as well as halide to afford a co-crystallised mixture of [Ni(6-Mes)(η²-C₆H₅Me)][B(C₆F₅)₄] (4), and [6MesH⋯C₆H₅Me][B(C₆F₅)₄]. Treatment of 1 with sodium salts of more strongly coordinating anions leads to substitution products. Thus, NaBH₄ yields the neutral, diamagnetic dimer [{Ni(6-Mes)}₂(BH₄)₂] (6), whereas NaBH₃(CN) gives the paramagnetic monomeric cyanotrihydroborate complex [Ni(6-Mes)(PPh₃)(NCBH₃)] (7). Treatment of 1 with NaO^tBu/NHPh₂ affords the three-coordinate Ni(I) amido species, [Ni(6-Mes)(PPh₃)(NPh₂)] (8). The electronic structures of 2, 5, 7 and 8 have been analysed in comparison to that of previously reported 1 using a combination of EPR spectroscopy and density functional theory.

The demand for nanocomposites of graphene and carbonaceous materials decorated with metallic nanoparticles is increasing on account of their applications in science and technology. Traditionally, the production of graphene-metal assemblies is achieved by the non-environmentally friendly reduction of metallic salts in carbonaceous suspensions. However, precursor residues during nanoparticle growth may reduce their surface activity and promote cross-chemical undesired effects. In this work we present a laser-based alternative to synthesize ligand-free gold nanoparticles that are anchored onto the graphene surface in a single reaction step. Laser radiation is used to generate highly pure nanoparticles from a gold disk surrounded by a graphene oxide suspension. The produced gold nanoparticles are directly immobilized onto the graphene surface. Moreover, the presence of graphene oxide influences the size of the nanoparticles and its interaction with the laser, causes only a slight reduction of the material. This work constitutes a green alternative synthesis of graphene-metal assemblies and a practical methodology that may inspire future developments.

The development of a synthetic modular methodology for the preparation of catalytic materials based on magnetic nanoparticles with iridium complexes and their application to transfer hydrogenation.

Catalytic hydrodefluorination of organic molecules is a major organometallic challenge, owing to the strength of C–F sigma bonds, and it is a process with multiple industrial applications. Here we report a new heterodimetallic ruthenium–palladium complex based on a triazolyl-di-ylidene ligand. The complex is remarkably active in the hydrodefluorination of aromatic and aliphatic carbon–fluorine bonds under mild reaction conditions. We observe that both metals are required to promote the reaction process. The overall process implies that the palladium fragment facilitates the C–F activation, whereas the ruthenium centre allows the reduction of the substrate via transfer hydrogenation from isopropanol/sodium t-butoxide. The activity of this heterodimetallic complex is higher than that shown by a mixture of the related homodimetallic complexes of ruthenium and palladium, demonstrating the catalytic benefits of the heterodimetallic complex linked by a single-frame ligand.