Binary transition metal sulfide

The structural chemistry of the actinides is often similar to that of lighter transition metals, such as Zr and Hf, and to that of the lanthanides however, the diffuse nature of the 5/ orbitals leads to some differences and specifically to interesting magnetic and electrical properties. The actinide sulfides are generally isostructural with the selenides, but not with the analogous tellurides. The binary chalcogenides of uranium and thorium have been discussed in detail [66], but the structural... 

Binary systems of ruthenium sulfide or selenide nanoparticles (RujcSy, RujcSey) are considered as the state-of-the-art ORR electrocatalysts in the class of non-Chevrel amorphous transition metal chalcogenides. Notably, in contrast to pyrite-type MS2 varieties (typically RUS2) utilized in industrial catalysis as effective cathodes for the molecular oxygen reduction in acid medium, these Ru-based cluster materials exhibit a fairly robust activity even in high methanol content environments of fuel cells. 

The promotion of bulk binary sulfide is limited exclusively to the promotion of molybdenum and tungsten by the first-row transition metal. The effect of the structural promotion (creating more of the same sites) is always coupled to the electronic promotion (creating more active sites). One ap-... 

Molecules and solids based on cubic rather than octahedral motifs are less abundant in chemistry. The former were treated in Section 5.2.5 and now we consider a few solid-state analogs. Similar cubic architectures are found in (Fe/Co/Ni Ss, or synthetic C09S8 transition-metal sulfide minerals called pentlandites. In a binary... 

Binary Transition Metal Sulfide Hydrodesulfurization (HDS) Catalysts... 

Crystal structure plays a secondary role in catalysis by the Transition Metal Sulfides. As the periodic trends for HDS of the binary sulfides shows the dominant effect is which transition metal is present in the reaction, this transition metal takes on the structure and stoichiometry of the phase which is most stable in the sulfur containing catalytic environment. The unsupported promoted catalyst systems can be grouped into "synergic" pairs of sulfides. Because these pairs are related to the basic periodic trends of the binary Transition Metal Sulfides through average heats of formation. 

Within this context, the present article concentrates on transition metal cluster complexes of cobalt, iron and manganese with mixed chalcogen/carbonyl ligand spheres obtained by reaction of simple binary metal carbonyls with alkali-metal sulfides, alkali-metal thiolates or transition-metal thiolate complexes and their selenium or tellurium counterparts. 

The discussion above has been directed principally to thermally induced spin transitions, but other physical perturbations can either initiate or modify a spin transition. The effect of a change in the external pressure has been widely studied and is treated in detail in Chap. 22. The normal effect of an increase in pressure is to stabilise the low spin state, i.e. to increase the transition temperature. This can be understood in terms of the volume reduction which accompanies the high spin—dow spin change, arising primarily from the shorter metal-donor atom distances in the low spin form. An increase in pressure effectively increases the separation between the zero point energies of the low spin and high spin states by the work term PAV. The application of pressure can in fact induce a transition in a HS system for which a thermal transition does not occur. This applies in complex systems, e.g. in [Fe (phen)2Cl2] [158] and also in the simple binary compounds iron(II) oxide [159] and iron(II) sulfide [160]. Transitions such as those in these simple binary systems can be expected in minerals of iron and other first transition series metals in the deep mantle and core of the earth. 

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