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Two imidazolylidene (Im) complexes of the general formula trans -[PdX2(Im)(pyridine)] (X = Cl (2), Br (3)), in which the N -heterocyclic carbene ligand has one of its nitrogen atoms substituted by a bulky 9-propyl-9-fluorenyl group (Pr F), have been prepared and fully characterised by spectroscopic methods and single-crystal X-ray structure analyses. In the solid state, the Im ring plane and the coordination plane of each complex are nearly orthogonal, thereby minimising the steric interactions between the N-substituents and the halide atoms. In both structures two methylenic C–H bonds sit near the d z 2 axis point to the palladium atom, resulting in CH⋯Pd separations of 2.58/2.95 Å in 2 and 2.74/2.74 Å in 3. NMR measurements and DFT calculations indicate that these methylene groups are involved in anagostic CH⋯M interactions but not in significant H⋯X bonding. The stepwise synthesis of two palladium(II) complexes containing an N -heterocyclic carbene ligand substituted by the bulky 9-propyl-9-fluorenyl group is described. In both complexes, two methylenic H atoms of the propyl group interact with the metal atom in an anagostic manner. [ABSTRACT FROM AUTHOR]

A series of new Pd–PEPPSI complexes containing imidazolylidene ligands with a mixed 9-alkyl-9-fluorenyl/aryl N,N′-substitution pattern have been synthesised. Single crystal X-ray diffraction studies were carried out for four complexes, which revealed that the N-heterocyclic carbene ligands display a semi-open, unsymmetrical space occupancy about the metal. Despite their particular unsymmetrical shape, the new complexes were found to perform as well in Suzuki–Miyaura cross coupling (dioxane, 80 °C) as previously reported, highly active analogues bearing two sterically protecting 9-alkylfluorenyl substituents. They were further found to be considerably more active than the standard Pd–PEPPSI complexes [PdCl2IMes(pyridine)] and [PdCl2IPr(pyridine)]. Surprisingly, unlike the latter, the unsymmetrical complexes of this study were practically inactive in isopropanol at 80 °C. Under these conditions the complexes appear to decompose with formation of non-stabilised nanoparticles. [ABSTRACT FROM AUTHOR]

Heck arylation of acrolein dialkyl acetal with (hetero)-aryl halides in water catalyzed by solid palladium catalysts and in presence of cyclodextrins is reported. Depending on the nature of the base, either cinnamaldehyde or 3-aryl propionic ester is obtained. It was shown that the presence of cyclodextrins in the reaction media increased the reaction rate as well as the stability of the palladium species. [ABSTRACT FROM AUTHOR]

Bimetallic platinum-ruthenium nanoparticles stabilised by pyridine- and monophosphine-based ligands were prepared either in supercritical CO2 or in THF. TEM analyses evidenced a tendency of the nanoparticles prepared in supercritical CO2 to agglomerate. Both types of bimetallic nanoparticles were further confined into functionalised multiwalled carbon nanotubes. Upon confinement, PtRu nanoparticles stabilised by phosphine ligands appeared more agglomerated than those stabilised by the pyridine ligand. These materials were applied to cinnamaldehyde hydrogenation. Confined PtRu nanoparticles showed higher catalytic activity and selectivity than unsupported nanoparticles. [ABSTRACT FROM AUTHOR]

Fully palladium/copper catalytic oxidative cross-coupling of acrylates with α-methylstyrene was performed in a DMSO/AcOH (1:1) mixture at 60 °C in the air. This improves previous procedures which employed stoichiometric amounts of copper and oxygen. Thus various acrylates were effectively coupled to α-methylstyrene giving the expected compounds in moderate to good yields (44%-65%) as a mixture of E and Z isomers. [ABSTRACT FROM AUTHOR]

A picture of nanoparticles is presented.