The thermal deactivation of engine-aged Pd/CeO2–ZrO2 three-way catalysts was studied by chassis-dynamometer driving test cycles with cold start and in situ diffuse reflectance spectroscopy (DRS). The extent of the catalyst deactivation after engine-aging at 800–1000 °C was correlated with the microstructural evolution, which was analyzed by X-ray diffraction, X-ray absorption spectroscopy, electron microscopy, and a chemisorption technique. This suggests that deactivation is caused by degradation of the catalytically active sites in the three-phase boundary (TPB) region, where Pd, CeO2–ZrO2, and the gas phase meet. The time-resolved in situ DRS revealed that the reoxidation of Pd metal under fluctuating air-to-fuel ratios was retarded relative to the reduction of Pd oxide. The retardation is attributable to the oxygen storage in CeO2–ZrO2. In the fresh catalyst with a high dispersion, most Pd was close to the TPB. Conversely, after engine-aging at elevated temperatures, the retardation effect was less pronounced with respect to Pd particle growth. Grown into large Pd particles, the Pd at sufficient distances from the TPB was no longer affected by the oxygen storage. Consequently, from the ratios of the initial rate constants of the Pd oxidation and reduction under fluctuating air-to-fuel ratio conditions, we can understand the quality and/or quantity of the TPB site in engine-aged catalysts. This measure provides a useful index of the extent of catalyst deactivation.

Changing places: A chain‐to‐sheet rearrangement of the Pd4 moiety (see picture; spheres: Pd, support: organic ligand) takes place during the exchange of one perylene or fluoranthene ligand of a bis(perylene) or a bis(fluoranthene) tetrapalladium sandwich complex by 1,3,5,7‐cyclooctatetraene. These findings are established by X‐ray crystallography and NMR spectroscopy.

The intramolecular oxidative addition of the C−H bond of N-(2-(diphenylphosphino)benzylidene)-2-phenylethylamine (PN) in Pt(PN)3 (1) to give cis-Pt[η2-o-P(Ph)2C6H4CN(CH2)2Ph](H)(PN) (3) proceeded reversibly under mild conditions. The enthalpy and the entropy of the equilibrium between 1 and (3 + PN) (ΔH° = 38.0(8) kJ/mol, ΔS° = 23.2(6) eu) suggested that the oxidative addition of the imine C−H bond to Pt(0) is unfavorable in terms of the enthalpy but is driven by the contribution of the entropy.

Two discrete hexadecavanadates, (n-Bu4N)4[V16O38(X)] (X = Cl(-) (1) and X = Br(-) (2)), were synthesized by a reaction of [V10O26](4-) with a template anion resulting in the incorporation of chloride or bromide in the {V16} spherical cluster framework. The reaction of [V10O26](4-) with p-toluenesulfonic acid proceeded under an aerobic environment to give 2 in the presence of an excess amount of bromide anion, which acted as both a template anion and a reducing reagent for the formation of the mixed-valence framework. For the synthesis of cluster 1, additional reductive conditions were required due to the weak reducing ability of the chloride anion. The crystal structures of 1 and 2 were determined using single-crystal X-ray diffraction analysis. Both were found to consist of a discrete [V(V)9V(IV)7O38(X)](4-) framework by the linkage of VO5 pyramidal units. Cyclic voltammetric studies of 1 and 2 in acetonitrile showed a series of stepwise reversible redox processes, which were due to the redox of the spherical polyoxovanadate frameworks. The oxidative bromination reactions of aromatic substrates were also investigated using cluster 2 as a catalyst under aerobic conditions.

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