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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 triazolyldi-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.

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.

RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required according to the journal that you are submitting your paper to) 2 ABSTRACTThe co-immobilization of palladium and ruthenium complexes with pyrene-tagged Nheterocyclic carbene ligands onto reduced grahene oxide allows the formation of a highly efficient catalyst for the hydrodefluorination of a series of fluoroarenes. This procedure constitutes an easy one-pot preparation of materials with homogeneously distributed polymetallic catalysts. The catalytic system can be recycled for up to twelve times without measurable loss of activity. The activity of the catalyst is attributed to the synergistic action of the two metals.

The catalytic dehydrogenative coupling of silanes and alcohols represents a convenient process to produce hydrogen on demand. The catalyst, an iridium complex of the formula [IrCp*(Cl) 2 (NHC)] containing an NHC ligand functionalized with a pyrene tag, catalyzes efficiently the reaction at room temperature producing H 2 quantitatively within a few minutes. As a result, the dehydrogenative coupling of 1,4-disilabutane and methanol enables an effective hydrogen storage capacity of 4.3 wt% that is as high as the hydrogen contained in the dehydrogenation of formic acid, positioning the silane/alcohol pair as a potential liquid organic hydrogen carrier for energy storage. In addition, the heterogenization of the iridium complex on graphene presents a recyclable catalyst that retains its activity for at least ten additional runs. The homogeneous distribution of catalytic active sites on the basal plane of graphene prevents diffusion problems and the reaction kinetics are maintained after immobilization.