Chevrel phase compounds

Chevrel phase compounds, AxMo6Ch8 (Ch = S, Se or Te), may also be considered as intercalation compounds. Mo6S8 can be prepared by acid-leaching copper from CuxMo6S8. 

H.-L.Luo Thin-Film Ternary Superconductors. - H.Nohl, W.Klose, O.K Andersen Band Structures of MxMogXg- and M2Mo6X6-Cluster Compounds. - S.D. Bader, S.K.Sinha, B.P.Schweiss, B.Renker Phonons in Ternary Molybdenum Chalcogenide Superconductors. -F.Pobell, D. Rainer, H. Wiihl Electron-Phonon Interaction in Chevrel-Phase Compounds. - Subject Index. 

The tolerance of chalcogenide was reported a long time ago using the Chevrel Phase compound. Some years later this property was documented with the cluster-like compounds of RuxSCy comparing them with the platinum electrode performance coupling the mass spectrometry (DBMS) to the electrochemical cell. ... 

Perspectives for fabrication of improved oxygen electrodes at a low cost have been offered by non-noble, transition metal catalysts, although their intrinsic catalytic activity and stability are lower in comparison with those of Pt and Pt-alloys. The vast majority of these materials comprise (1) macrocyclic metal transition complexes of the N4-type having Fe or Co as the central metal ion, i.e., porphyrins, phthalocyanines, and tetraazaannulenes [6-8] (2) transition metal carbides, nitrides, and oxides (e.g., FeCjc, TaOjcNy, MnOx) and (3) transition metal chalcogenide cluster compounds based on Chevrel phases, and Ru-based cluster/amorphous systems that contain chalcogen elements, mostly selenium. 

The different classes of Ru-based catalysts, including crystalline Chevrel-phase chalcogenides, nanostructured Ru, and Ru-Se clusters, and also Ru-N chelate compounds (RuNj), have been reviewed recently by Lee and Popov [29] in terms of the activity and selectivity toward the four-electron oxygen reduction to water. The conclusion was drawn that selenium is a critical element controlling the catalytic properties of Ru clusters as it directly modifies the electronic structure of the catalytic reaction center and increases the resistance to electrochemical oxidation of interfacial Ru atoms in acidic environments. 

The situation is very similar in the Chevrel phases. These are ternary molybdenum chalcogenides A,.[Mo6Xg] (A = metal, X = S, Se) that have attracted much attention because of their physical properties, especially as superconductors. The parent compound is PbMo6Sg it contains Mo6Sg clusters that are linked with each other in such a way that the free coordination sites of one cluster are occupied by sulfur atoms of adjacent clusters (Fig. 13.9). The electric properties of Chevrel phases depend on the number of valence electrons. With 24 electrons per cluster (one electron pair for each edge of the... 

A detailed example of the alternative descriptions of a given compound, both in terms of its hexagonal unit cell and of the corresponding rhombohedral primitive cell is presented in Chapter 4 the rhombohedral compound Mo6PbSx (the prototype of the family of the so-called Chevrel phases) is described and unit cell constants and atomic positions are listed for its conventional hexagonal cell and for the rhombohedral primitive cell. 

Cu4Mo6Seg. The triclinic structure of these compounds has been described by McGuire et al. (2006). It contains nearly regular Mo6 clusters the Cu atoms fully occupy four sites between faces of two adjacent Mo6Se8 clusters. This compound is a member of a series of MexMogX8 Chevrel phases. Preparation and properties have been discussed. A Cu intercalation apparatus was built for... 

The Chevrel phases are structure containing clusters as building blocks and they may be considered as phases having characteristics at the borderline between those of compounds containing molecular-like units and of solids containing infini-tively extended units. Such phases have been described in 4.4.4.7 together with Mo6X8 clusters and the products of their condensation. 

X-ray crystallography, 40 20-21 synthetic models, 40 23-48 xanthane oxidase, 40 21-23 chalcogenide halides, 23 370-377, 413 Chevrel phases, 23 376-377 metal-metal bonding, 23 330, 373 structural data, 23 373-376 as superconductors, 23 376 synthesis, 23 371-372 chloride, 46 4-24, 35-44 heterocations of, 9 290, 291 cluster compounds, 44 45-46 octahedral, 44 47-49, 53-63 electronic structure, 44 55-63 molecular structure, 44 53-54 synthesis, 44 47-49 rhomboidal, 44 75-82 solid-state clusters and, 44 66-72, 74-75, 80-82, 85-87 tetrahedral, 44 72-75 triangular, 44 82-87 cofactor, 40 2, 4-12 anaerobic isolation, 40 5 molybdopterin and, 40 4-8 reduced form, 40 12 synthesis, 40 8-12 xanthine oxidase, 45 60-63 complexes... 

---