Alessandra Merigo

Halo-carbonyl complexes of platinum(II) and palladium(II)

Abstract The mononuclear and binuclear square-planar complexes of palladium(II) and platinum(II) cis-PtCl2(CO)2 (1), trans- Pt2Cl4(CO)2 (2), cis-PtBr2(CO)2 (3), and cis-Pd2Cl4(CO)2 (4), have been prepared by new synthetic procedures and some of them (2, 3, and 4) structurally characterised by X-ray diffraction methods. In the mononuclear platinum derivatives, cis-PtX2(CO)2, X=Cl, Br, the molecules are arranged in columns, the Pt⋯Pt separation being 3.378 A (X=Cl) or 3.65 A (av., X=Br). The chloride-bridged dinuclear chloro-carbonyl complexes M2Cl4(CO)2, M=Pd, Pt, contain terminal chloride and carbonyl groups, trans for the platinum derivative 2, but, unexpectedly, cis for the corresponding palladium compound 4. Packing is based on intermolecular C⋯X or Pt⋯Pt interactions, as a function of the nature of the halide. The carbonylation at atmospheric pressure and room temperature of the tetrahalo complexes of platinum(II) in the presence of AlX3 as halide scavenger leads to [PtX3(CO)]− or PtX2(CO)2, depending on the Pt/AlX3 molar ratio. The crystal and molecular structural data of [NBu4][PtBr3(CO)] (5), show the anion to have substantially identical Pt–Br bond distances, the CO ligand performing no trans influence.

IMPROVED PREPARATION OF ANHYDROUS LANTHANIDE CHLORIDES UNDER MILD CONDITIONS

Abstract Oxides or carbonates of lanthanides (Ln) are converted under mild conditions into the corresponding solvated anhydrous chlorides LnCl 3 (ether) n by hydrogen chloride produced in situ from thionyl chloride and water in the presence of 1,l2-dimethoxyethane under mild conditions.

Loading silica with metals (palladium or platinum) under mild conditions by using well-defined molecular precursors

The loading of pre-treated amorphous silica with platinum or palladium was carried out by using the molecular precursors Pt2(micro-Cl)2Cl2(CO)2, or Pd2(micro-Cl)2Cl2(CO)2, respectively, which contain the required amount of coordinated CO to carry out the formation of the metal particles upon contact with moisture. The reactivity of the well-soluble mononuclear platinum complex cis-PtCl2(CO)2 with stoichiometric amounts of water was investigated either under N2 or CO. The metal nanoparticles produced on the silica matrix have been characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The catalytic performance of the silica-supported metals thus produced was evaluated in the hydrogenation of cyclohexene.

Isotypical N,N-dialkylcarbamato lanthanide complexes covering a range of 11 atomic numbers: direct experimental assessment of the lanthanide contraction in trivalent molecular compounds

The N,N-diisopropylcarbamato complexes of lanthanides(III) from neodymium (Z = 60) to ytterbium (Z = 70) were found to be isotypical, with Ln–O distances decreasing steadily with increasing Z, the lanthanide contraction in this series of molecular complexes being provisionally assigned to an increasing bond strength with increasing atomic number of the central metal atom.