No abstract

phinomethyl)pyridine) have been prepared and characterized by 1 H and 13 C NMR spectroscopy, and the molecular structure of the ethylene complex has been determined by X-ray diffraction analysis. Nucleophilic attack at the coordinated double bond takes place more readily than for known neutral and monocationic species, and a variety of protic nucleophiles NuH (MeOH, H 2 O, aromatic amines) give the corresponding -functionalized σ-alkyl complexes [Pt(PNP)(CHRCHR′Nu)]BF 4 also in the absence of auxiliary bases. In the case of the styrene derivatives an unusual decomposition pathway gives the stable alkenyl complex [Pt(PNP)(CHdCHPh)]BF 4 . A competitive equilibrium process between substitution and addition was revealed by reacting ethylene with the isolated aniline complex [Pt(PNP)-(PhNH 2 )](BF 4 ) 2 . The nucleophilic addition product was found to be thermodynamically favored over the substitution product more than in the case of the analogous palladium complexes.

Dicationic olefin palladium(II) complexes [Pd(PNP)(olefin)](BF4)2 [olefin = ethylene, propene, styrene, (Z)‐2‐butene, (E)‐2‐butene, norbornene; PNP = 2,6‐bis(diphenylphosphanylmethyl)pyridine] have been prepared and characterized by 1H, 13C, and 31P NMR spectroscopy. The coordinated double bond in these complexes is strongly electrophilic, and easily adds a variety of nucleophiles NuH (H2O, MeOH, aliphatic and aromatic amines). This reaction competes with olefin displacement in a rapidly reversible equilibrium process, as a result of which the addition products can also be obtained starting from the substituted compounds [Pd(PNP)(NuH)](BF4)2 and the appropriate olefin. Equilibrium constants for the addition and substitution reactions have been determined in a number of cases. Proton abstraction from [Pd(PNP)(CHRCHR′NuH)]2+ by NaHCO3 quantitatively drives the equilibrium to β‐functionalized alkyl complexes of the general formula [Pd(PNP)(CHRCHR′Nu)](BF4), which are unusually stable to β‐H elimination.

We report on the self-assembling of clusters of gold-nanoparticles (Au-NPs) directed by the phase separation of poly(styrene)-b-poly(methylmethacrylate) (PS-b-PMMA) block-copolymer (BCP) on indium tin oxide coated glass, which induces the onset of vertical lamellar domains. After thermal evaporation of gold on BCP, Au-NPs of 4 nm are selectively included into PS-nanodomains by thermal annealing, and then clustered with large density of hot spots (> 10(4) μm(2)) in a random two-dimensional pattern. The resulting nanostructure exhibits near-hyperuniform long-range correlations. The consequent large degree of homogeneity of this isotropic plasmonic pattern gives rise to a highly reproducible Surface-Enhanced Raman Scattering (SERS) enhancement factor over the centimeter scale (std. dev. ∼ 10% over 0.25 cm(2)). We also discuss the application of a static electric field for modulating the BCP host morphology. The electric field induces an alignment of Au-NP clusters into ordered linear chains, exhibiting a stronger SERS activity, but reduced SERS spatial reproducibility.