Synthesis of water-soluble ruthenium clusters by reaction with PTA (1,3,5-triaza-7-phosphaadamantane)

The Backbone of Success of P,N-Hybrid Ligands: Some Recent Developments

Organophosphorus ligands are an invaluable family of compounds that continue to underpin important roles in disciplines such as coordination chemistry and catalysis. Their success can routinely be traced back to facile tuneability thus enabling a high degree of control over, for example, electronic and steric properties. Diphosphines, phosphorus compounds bearing two separated PIII donor atoms, are also highly valued and impart their own unique features, for example excellent chelating properties upon metal complexation. In many classical ligands of this type, the backbone connectivity has been based on all carbon spacers only but there is growing interest in embedding other donor atoms such as additional nitrogen (-NH-, -NR-) sites. This review will collate some important examples of ligands in this field, illustrate their role as ligands in coordination chemistry and highlight some of their reactivities and applications. It will be shown that incorporation of a nitrogen-based group can impart unusual reactivities and important catalytic applications.

1,1,2,2,2,3,3,3-Octa-carbonyl-1,1,2,3-tetra-kis-(1,3,5-tri-aza-7-phosphatri-cyclo-[3.3.1.13,7]decane-κP)-triangulo-triosmium(0)

The title compound, [Os3(C6H12N3P)4(CO)8], crystallizes in the ortho-rhom-bic space group Pbca with Z = 8. The mol-ecule consists of a triangular triosmium(0) core surrounded by eight carbonyl ligands and four 1,3,5-tri-aza-7-phosphatri-cyclo-[3.3.1.13,7]decane (or PTA) ligands. One Os atom is coordinated by two PTA ligands and two CO ligands, while the other two Os atoms are each bonded to a single PTA ligand and three CO ligands. There is a small disorder associated with the Os3 unit so that a minor orientation has an occupancy of 2.17 (4)%. The title compound represents the first structurally characterized triangular Os3 carbonyl cluster with four monodentate tertiary phosphane ligands.

Water soluble derivatives of platinum carbonyl Chini clusters: synthesis, molecular structures and cytotoxicity of [Pt12(CO)20(PTA)4]2- and [Pt15(CO)25(PTA)5]2-

The reactions of [Pt3n(CO)6n]2- (n = 2-5) homoleptic Chini-type clusters with increasing amounts of 1,3,5-triaza-7-phosphaadamantane (PTA) result in the stepwise substitution of one terminal CO ligand per Pt3 triangular unit up to the formation of [Pt3n(CO)5n(PTA)n]2- (n = 2-5). Competition between the nonredox substitution with retention of the nuclearity and the redox fragmentation to afford lower nuclearity heteroleptic Chini-type clusters is observed as a function of the amount of PTA and the nuclearity of the starting cluster. Because of this, [Pt12(CO)20(PTA)4]2- and [Pt15(CO)25(PTA)5]2- are more conveniently obtained via the oxidation of [Pt9(CO)15(PTA)3]2-. All the new species were spectroscopically characterized, and the structures of [Pt12(CO)20(PTA)4]2- and [Pt15(CO)25(PTA)5]2- were determined by single-crystal X-ray diffraction. These clusters may be viewed as heteroleptic Chini-type clusters composed of stacks of four and five Pt3(μ-CO)3(CO)2(PTA) units, respectively. The solubility in water of [Pt12(CO)20(PTA)4]2- and [Pt15(CO)25(PTA)5]2- has been determined and their cytotoxicity towards human ovarian (A2780) cancer cells and their cisplatin-resistant strain (A2780cisR) has been evaluated.

pH controlled adsorption of water-soluble ruthenium clusters onto carbon nanotubes and nanofiber surfaces

Nanocarbon supported catalysts were prepared from water-soluble molecular clusters by pH controlled impregnations in order to probe the clusters/surface interactions and to maximize them.