Clústeres Sulfuro Trimetálicos de Molibdeno y Wolframio Funcionalizados con Ligandos Difosfina o Aminofosfina y sus Aplicaciones en Catálisis Orgánica

The research work described in this thesis presents the synthesis, characterization and properties of a new family of trimetallic M 3 (μ 3 -S)(μ 2 -S) 3 molybdenum and tungsten sulfide clusters. Functionalization of the cluster unit has been done by incorporating different chelating ligands such as diphosphines and heterodentate aminophosphines in order to confer specific physicochemical properties such as water solubility or catalytic activity. In particular, water soluble diphosphines and aminophosphines have been coordinated to the M 3 S 4 unit in order to evaluate the potential applications of these new derivatives in environmentally friendly biphasic catalysis and homogenous organic catalysis, respectively. The first chapter of the thesis describes the background, relevance and importance of the chemistry of transition metal clusters. General aspects on the chemistry of molybdenum and tungsten trinuclear clusters are shown together with their last novel applications. The second chapter shows the main objectives of this research project. The preparation and characterization of novel water soluble cluster compounds of formula [M 3 S 4 X 3 (hydroxyalkyldiphosphine) 3 ] + (M=Mo, W; X=Cl, Br; hydroxyalkyldiphosphine = dhprpe, dhbupe) is described in chapter 3. Detailed studies based on 31 P{ 1 H} NMR and electrospray ionization mass spectrometry techniques have been carried out in order to understand the complex pH dependent aqueous speciation of these water soluble clusters. In chapter 4, the synthesis of molybdenum (IV) hydroxo [Mo 3 S 4 (dmpe) 3 (OH) 3 ] + and hydrosulfido [Mo 3 S 4 (dmpe) 3 (SH) 3 ] + trimetallic cuboidal cluster complexes is presented. A comparative study between molybdenum and tungsten of the gas-phase aldehyde production from the M 3 S 4 ethoxo complexes combining collision induced dissociation experiments with computational DFT calculations is also discussed. In chapter 5, the catalytic activity of molybdenum and tungsten (IV) cluster hydrides of formula [M 3 S 4 H 3 (dmpe) 3 ] + (M=Mo, W) in the regioselective hydrodefluorination of pentafluoropyridine at the 4-position has been evaluated. A mechanism for the catalytic reaction has been proposed based on experimental results and DFT calculations. Additionally, the fluorinated [M 3 S 4 F 3 (dmpe) 3 ] + complexes have been fully characterized. In chapter 6, an aminophosphine ligand, (2-aminoethyl)diphenylphosphine (edpp), containing a NH 2 protonic function has been coordinated to t