Molecular precursor

Douglas T and Theopold K H 1991 Molecular precursors for indium phosphide and synthesis of small lll-V semiconductor clusters in solution inorg. Chem. 30 594... 

The formation of PAHs and soot involves a molecular precursor stage in which hydrocarbon radicals, especially with 2-5 carbon atoms, play a role to build up... 

The sacrificial core approach entails depositing a coating on the surface of particles by either the controlled surface precipitation of inorganic molecular precursors from solution or by direct surface reactions [2,3,5,6,8,9,33-35,38], followed by removal of the core by thermal or chemical means. Using this approach, micron-size hollow capsules of yttrium compounds [2], silica spheres [38], and monodisperse hollow silica nanoparticles [3,35] have been generated. 

EXAFS characterization of supported PtRu/MgO prepared from a molecular precursor and organometallic mixture... 

Step (3), the recombination of adsorbed oxygen and adsorbed CO to give adsorbed CO2, is assumed to be the rate-limiting step. We could describe step (2) in more detail, as the adsorption of O2 proceeds via a molecular precursor, O2, which subsequently dissociates. However, for simplicity, we neglect this elementary step, leaving it to the reader to determine the consequences of taking it into account. 

The interaction of hydrogen (deuterium) molecules with a transition metal surface c an be conveniently described in terms of a Lennard--Jones potential energy diagram (Pig. 1). It cxxislsts of a shallcw molecular precursor well followed by a deep atomic chemisorption potential. Depending on their relative depths and positions the wells m or may not be separated by an activation energy barrier E as schematically Indicated by the dotted cur e in Fig. 1. 

Abstract A review of the thermolytic molecular precursor (TMP) method for the generation of multi-component oxide materials is presented. Various adaptations of the TMP method that allow for the preparation of a wide range of materials are described. Further, the generation of isolated catalytic centers (via grafting techniques) and mesoporous materials (via use of organic templates) is simimarized. The implications for syntheses of new catalysts, catalyst supports, nanoparticles, mesoporous oxides, and other novel materials are discussed. 

Multicomponent oxide Thermolytic molecular precursor (TMP) method... 

Tailored Oxide Materials via Thermolytic Molecular Precursor (TMP) Methods... 

Molecular precursors appropriate for use in the TMP method are typically oxygen-rich complexes of the form L M[OxE(OR) ]z, where L = alkoxide. 

Two principle strategies have been employed for the synthesis of siloxide-containing molecular precursors. The first involves a silanolysis, or condensation, reaction of the Si - OH groups with a metal amido, alkyl, hahde, or alkoxide complex. The second method involves salt metathesis reactions of an alkali metal siloxide with a metal hahde. Much of our work has been focused on formation of tris(tert-butoxy)siloxide derivatives of the early transition metals and main group elements. The largely imexplored regions of the periodic table include the lanthanides and later transition metals. 

Tris(ferf-butoxy)siloxide molecular precursors of V(IV) and V(V) can be prepared via simple silanolysis reactions. For example, OV[OSi(O Bu)3]3 was obtained in 85% yield by reaction of OVCI3 with excess HOSi(O Bu)3 in the presence of pyridine [79]. Although crystals of sufficient quality for an X-ray structural analysis of 0V[0Si(0 Bu)3]3 were not obtained, its identity was confirmed by various spectroscopic and analytical techniques. Additionally, ( BuO)3VOSi(O Bu)3 and ( BuO)2V[OSi(O Bu)3]2 were obtained via reaction of V(0 Bu)4 with 1 and 2 equiv of HOSi(O Bu)3, respectively, in toluene at 80 °C [80] (Eq. 5). Both (fBu0)3V0Si(0 Bu)3 and CBu0)2V[0Si(0 Bu)3]2 are monomeric in the solid state, and possess only monodentate siloxide ligands... 

The only group 8 tris(ferf-butoxy)siloxide molecular precursor that has been reported thus far is the iron(III) complex Fe[OSi(O Bu)3]3 THE, synthesized via the reaction of FeCls with NaOSi(0 Bu)3 in THF (74%) [71,97] (Eq. 6). An... 

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