Metal-oxygen clusters

Moffat, J. B. Metal-Oxygen Clusters The Surface and Catalytic Properties of Heteropoly Oxometalates vol. 9 Kluwer Academic/Plenum Publishers New York, 2001. 

In addition, such generic terms as metal-oxygen cluster ion, metal-oxide molecule, etc., are used for polyanions (and polyacids). Since the traditional heteropoly- and isopoly- are unsatisfactory terms to express a variety of polyacids and polyanions, the terms polyoxometalates and polyoxoacids have been used recently (3). The terminology is still changing, thus reflecting the rapid expansion of the chemistry. 

Heteropolyacids are condensates of different types of oxoacids and involve inorganic metal-oxygen clusters... 

Polyoxometallates (POMs) are a large class of nanosized transition metal-oxygen clusters [1]. Their structures, sizes and properties correspond to compounds intermediate between molecules and oxides. They are composed of anions having metal-oxygen octahedra as the basic structural unit. The octahedra are linked together to yield a stable and compact skeleton of polymeric oxoanions formed by the condensation of mononuclear oxoanions (isopolyanions) or of more than two different mononuclear oxoanions (heteropolyanions) in acidic media as shown in the equation ... 

Moffat, J.B. (2001) Metal-oxygen Clusters. The Surface and Catalytic properties of Heteropoly Oxometallates, Wuwer, New York, pp. 97-142. 

A. Mullee, P. Kogeelee, H. Bogge, Pythagorean Harmony in the World of Metal Oxygen Clusters of the Mon Type Giant Wheels and Spheres both Based on a Pentagonal Type Unit, Struct. Bonding 2000, 96, 203-236 and literature cited therein. 

Polyoxometalates encompass complexes known historically as heteropoly- and isopolyanions (or acids). Other labels, e.g., heteropoly electrolytes, metal-oxygen cluster anions, have also been applied from time to time. The present chapter will discuss only those complexes containing V, Nb, Ta, Mo, and/or W as the major component (the addenda atoms). The relatively small number of polyoxochromates is excluded, since Crvl is restricted to tetrahedral four-coordination by oxide, and these complexes are if anything more closely related to the nonmetal polyoxoanions like sulfates. 

Metal oxygen cluster compounds with keggin structure have received attention as acid catalysts for several acid catalysed reactions in the liquid as well as in vapour phase conditions [1-6]. Studies on a series of salts with monovalent cations and various heteropolyanions have revealed that certain of these solids in particular those containing potassium, cesium,ammonium and thallium cations possess microporous structure [7-11]. Photoacoustic FTIR investigations and the studies on the chemisorption of ammonia and pyridine have shown that residual protons remain and these protons are responsible for the catalytic activity[12,13]. 

Comm. 1347 (1999) A. Muller, P. Kogerler, and H. Bogge, Pythagorean harmony in the world of metal oxygen clusters ofthe MOn type giant wheels and spheres both based on apentagonal type unit. Struct. Bond. 96 203 (2000). 

Pythagorean Harmony in the World of Metal Oxygen Clusters of the Mo Type Giant Wheels and Spheres both Based on a Pentagonal Type Unit... 

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