Modeling multiple-valence compounds using density-functional theory has long been considered a formidable task due to the role that strong electronic correlations play in these systems. We show that, case of defective ceria, main effect is produce multitude metastable low-energy states among which one displaying correct valence cerium most stable. This ground state may be difficult access practice and it fact so far escaped proper identification. The introduction Hubbard-$U$ term energy...

The atomistic and electronic structures of oxygen vacancies on the (111) (110) surfaces ceria are studied by means periodic density functional calculations. removal a neutral surface atom leaves back two excess electrons that shown to localize cerium ions neighboring defect. resulting change valency these Ce (Ce 4+ → Ce3+) originates from populating tightly bound 4f states is modeled adding Hubbard U term traditional energy functionals. calculated defect-free reduced agree with spectroscopic...

Computer simulation techniques have been used to model cubic CeO2−ZrO2 solid solutions in the whole composition range. Aspects related with oxygen storage capacity of these materials are emphasized. The energetics Ce4+/Ce3+ bulk reduction reaction as well activation energy for migration lattice investigated and compared corresponding quantities pure CeO2. It is found that even small additions ZrO2 decrease Ce4+ values comparable those reported surface Activation calculations indicate an...

The (110), (111), and (310) surfaces of cubic CeO2−ZrO2 solid solutions have been studied by computer simulation techniques using atomistic models. Surface energies, Ce4+/Ce3+ reduction penetration profiles oxygen vacancy formation calculated. results the calculations suggest some possible factors that could explain increase in storage capacity experimentally observed these systems relative to pure ceria: surface energies are comparable with previously found bulk values; introduction...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, molecular structure, and chemical behavior of hydrogen trans-bis(dimethyl sulfoxide)tetrachlororuthenate(III) mer-trichlorotris(dimethyl sulfoxide)ruthenium(III): the first fully characterized chloride-dimethyl sulfoxide-ruthenium(III) complexesEnzo Alessio, Gabriele Balducci, Mario Calligaris, Giacomo Costa, Wahib M. Attia, Giovanni MestroniCite this: Inorg. Chem. 1991, 30, 4, 609–618Publication Date (Print):February 1, 1991Publication...

We address the issues raised in preceding Comment by discussing effects of an explicit account nonlinear core correction (NLCC) into Ce pseudopotential employed our previous calculations reduced ceria [Phys. Rev. B 71, 041102(R) (2005)]. At plain density-functional-theory (DFT) level, such brings results good agreement with all-electron ones, which do not predict insulating character ceria. $\mathrm{DFT}+U$ inclusion NLCC has no effect on previously reported electronic structure and...

Cubic solid solutions of general formula Ce1-xMxO2 (M = Zr, Th, Hf) have been modeled in the range (0 < x 1) using atomistic simulation methods. The Ce4+/Ce3+ reduction energy bulk materials and activation for oxygen migration calculated. decreases with increasing M content most remarkable effect being displayed Th. An opposite trend is obtained when Hf. content. Th similar to that Zr consists a substantial decrease at high concentrations. On other hand, only slightly

The interaction of the (110) and (111) surfaces ceria (CeO2) with atomic hydrogen is studied ab initio calculations based on density functional theory. A Hubbard U term added to standard allows accurately describe electronic structure two surfaces. minimum energy configuration for adsorbed H each obtained. An O−H−O bridge formed surface, whereas an axial tricoordinated OH group results surface. For both surfaces, adsorption atom accompanied by reduction a single Ce ion (which one nearest...

The migratory insertion reaction of a polar vinyl monomer into the Pd-alkyl bond and chain walking process are two key steps in catalytic cycle for synthesis functionalized polyolefins through coordination/insertion polymerization. Here, we present detailed NMR investigation to gain insight these fundamental demonstrate critical role traces MeCN this process. We used Pd(II) complexes containing N-N' bidentate pyridyl-pyridylidene amide (py-PYA) ligand, which known cooligomerize ethylene...

A computer simulation study of the Ce4+/Ce3+ reduction process in CeO2−MO (M = Ca, Mn, Ni, Zn) and CeO2−M2O3 Sc, Y, Gd, La) mixed oxides is presented. Calculations satisfactorily reproduce observed structural parameters solid solutions over a wide range compositions. On energetic grounds, enhanced with increasing dopant content, enhancement being more pronounced for divalent dopants. For fixed level, cerium favorable larger ions. The results are explained terms higher oxygen vacancy...

A 6-(2,6-dimethylphenyl)-2-(2,6-diisopropylphenyl)iminopyridine dibromo nickel(<sc>ii</sc>) complex was synthesized, characterized by X-ray diffraction analysis and tested in ethylene polymerization using diethylaluminumchloride as the cocatalyst.

The development of efficient homogeneous catalysts for the synthesis functionalized polyolefins is a challenging topic. Palladium(II) complexes with α-diimine ligands having phenanthrene skeleton and 2,6-disubstituted aryl rings (Ar-BIP) were synthesized, characterized, tested as precatalysts in copolymerization ethylene methyl acrylate. direct comparison analogous corresponding α-diimines an acenaphthene (Ar-BIAN) was performed. X-ray characterization solid state NMR analysis solution both...

The synthesis of functionalized polyolefins through coordination–insertion polymerization is a highly challenging reaction. ideal catalyst, in addition to showing high productivity, has be able control the copolymer microstructure and, particular, way polar vinyl monomer incorporation. In this contribution, we modified typical Brookhart's catalyst by introducing fourth coordination site palladium hemilabile, potentially bidentate ligand, such as thiophenimine (N–S). obtained cationic Pd(II)...

Four iminopyridines (N-N') differing in the nature of substituents on iminic carbon and ortho positions aryl ring (H or CH3) nitrogen were used for synthesis neutral monocationic palladium(ii) complexes general formulae [Pd(CH3)Cl(N-N')] [Pd(CH3)(NCCH3)(N-N')][PF6]. The detailed NMR characterization solution highlighted that: (i) both series complexes, Pd-CH3 signal is progressively shifted to a lower frequency increasing number methyl groups ligand skeleton; (ii) derivatives, chemical shift...

Abstract Pd II complexes with a nonsymmetrical bis(aryl‐imino)diazabutadiene ligand (ArDAB) have been synthesized and characterized. The new features one aryl ring substituted in the ortho positions methyl group other that bears trifluoromethyl on meta positions, which leads to subtle steric electronic differences at two N donor atoms. This peculiar substitution makes direct synthesis of unfeasible, relevant complex, [Pd(CH 3 )Cl(ArDAB)], is obtained directly through template reaction....

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemistry of iron(I) porphyrins in the presence carbon monoxide. Comparison with zinc porphyrinsGabriele Balducci, Genevieve Chottard, Claire Gueutin, Doris Lexa, and Jean-Michel SaveantCite this: Inorg. Chem. 1994, 33, 9, 1972–1978Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 April 1994https://pubs.acs.org/doi/10.1021/ic00087a038https://doi.org/10.1021/ic00087a038research-articleACS...

Abstract In four series of strictly related organocobalt complexes, derived from cobaloximes by replacement the O…H…O with O…‐BF 2 …O and/or (CH ) 3 groups, trends 59 Co‐NMR shielding and electrochemical data are discussed. A largely parallel behaviour plots E 1/2 (I) values for first Co(III)/Co(II) electron transfer vs. Co chemical shifts reflects similar sensitivity two parameters to a change in affinity central metal ion due variation organic group R. (II) second Co(II)/CO(I) less...