We introduce density functional theory and review recent progress in its application to transition metal chemistry. Topics covered include local, meta, hybrid, hybrid meta, and range-separated functionals, band theory, software, validation tests, and applications to spin states, magnetic exchange coupling, spectra, structure, reactivity, and catalysis, including molecules, clusters, nanoparticles, surfaces, and solids.

Density functional theory for transition metals and transition metal chemistry

Site Heterogeneous Catalysts: Strategies, Methods, Structures, and Activities Christophe Copeŕet,*,† Aleix Comas-Vives,† Matthew P. Conley,† Deven P. Estes,† Alexey Fedorov,† Victor Mougel,† Haruki Nagae,†,‡ Francisco Nuñ́ez-Zarur,† and Pavel A. Zhizhko†,§ †Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1−5, CH-8093 Zürich, Switzerland ‡Department of Chemistry, Graduate School of Engineering Science, Osaka University, CREST, Toyonaka, Osaka 560-8531, Japan A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str. 28, 119991 Moscow, Russia

Surface Organometallic and Coordination Chemistry toward Single-Site Heterogeneous Catalysts: Strategies, Methods, Structures, and Activities

The selective activation and transformation of alkanes or aromatics have been a research goal for several decades.1-3 Today, research in this area is strongly motivated by the need to optimize resources and to shorten the number of steps, hence the direct and selective transformation of petrochemicals into valuable products is therefore of major interest. Any of these processes will have first to rely on the selective C-H bond activation. This has been the holy grail in molecular organometallic chemistry and homogeneous catalysis for some years;1,4,5 several success stories have appeared in the past ten years,6-9 including progress in the direct catalytic functionalization of methane into methanol.10-13 However, finding stable catalytic systems using acceptable operating conditions remains a challenge. In heterogeneous catalysis, several large scale industrial processes are based on the selective C-H bond activation of alkanes and lead to the synthesis of more valuable and functionalized products in a single step, for instance the direct oxidation of butane into maleic anhydride,14-16 the dehydrogenation of propane into propene,17,18 or the direct transformation of liquefied petroleum gas (LPG) into aromatics.19-24 C-H bond activation is in fact a ubiquitous process in heterogeneous catalysis. It involves various types of mechanisms and intermediates. C-H bond activation involving carbonium and carbenium ion intermediates3,25-27 or taking place on metal particles (supported or not) or clean metal surfaces28-35 has been extensively reviewed in the past years. Here, we will focus on processes involving C-H bond activation of alkanes and aromatics on isolated metal centers of surfaces on oxide materials leading to organometallic species and/or intermediates. The review is divided into two main sections focusing on the C-H bond activation on oxide materials and related systems (section 2) and on well-defined organometallic complexes supported on oxide materials (section 3). Section 2 is subdivided into four parts describing C-H bond activation on bulk oxides, bulk metal halides, supported transition-metal oxides, and metal-exchange zeolites.

C−H Bond Activation and Organometallic Intermediates on Isolated Metal Centers on Oxide Surfaces

Combining experiments and DFT calculations, we show that tricoordinate Al(III) Lewis acid sites, which are present as metastable species exclusively on the major (110) termination of γ- and δ-Al(2)O(3) particles, correspond to the "defect" sites, which are held responsible for the unique properties of "activated" (thermally pretreated) alumina. These "defects" are, in fact, largely responsible for the adsorption of N(2) and the splitting of CH(4) and H(2). In contrast, five-coordinate Al surface sites of the minor (100) termination cannot account for the observed reactivity. The Al(III) sites, which are formed upon partial dehydroxylation of the surface (the optimal pretreatment temperature being 700 °C for all probes), can coordinate N(2) selectively. In combination with specific O atoms, they form extremely reactive Al,O Lewis acid-base pairs that trigger the low-temperature heterolytic splitting of CH(4) and H(2) to yield Al-CH(3) and Al-H species, respectively. H(2) is found overall more reactive than CH(4) because of its higher acidity, hence it also reacts on four-coordinate sites of the (110) termination. Water has the dual role of stabilizing the (110) termination and modifying (often increasing) both the Lewis acidity of the aluminum and the basicity of nearby oxygens, hence the high reactivity of partially dehyxdroxylated alumina surfaces. In addition, we demonstrate that the presence of water enhances the acidity of certain four-coordinate Al atoms, which leads to strong coordination of the CO molecule with a spectroscopic signature similar to that on Al(III) sites, thus showing the limits of this widely used probe for the acidity of oxides. Overall, the dual role of water translates into optimal water coverage, and this probably explains why in many catalyst preparations, optimal pretreatment temperatures are typically observed in the "activation" step of alumina.

γ-Alumina: the essential and unexpected role of water for the structure, stability, and reactivity of "defect" sites.

Many industrial catalysts contain isolated metal sites on the surface of oxide supports. While such catalysts have been used in a broad range of processes for more than 40 years, there is often a very limited understanding about the structure of the catalytically active sites. This review discusses how Surface Organometallic Chemistry (SOMC) engineers surface sites with well-defined structures and provides insight about the nature of active sites in industrial catalysts, focusing in particular on olefin production and conversion processes

/pdf/bridging-the-gap-between-industrial-and-well-defined-4f3dacemos.pdf

Bridging the Gap between Industrial and Well-Defined Supported Catalysts

Synthesis, Characterization, and Catalytic Properties of γ-Al2O3-Supported Zirconium Hydrides through a Combined Use of Surface Organometallic Chemistry and Periodic Calculations

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Synthesis, Characterization, and Catalytic Properties of γ-Al2O3-Supported Zirconium Hydrides through a Combined Use of Surface Organometallic Chemistry and Periodic Calculations