Arsenic clusters

Alkali Metal-Phosphorus and Alkali Metal-Arsenic Clusters I 403... 

Metal-Phosphorus and Alkali Metal—Arsenic Clusters I 409... 

Alkaline-earth Metal- and Tin(+2)-Phosphorus and -Arsenic Clusters... 

Alkaline-earth Metal—and Tin(+2)—Phosphorus and—Arsenic Clusters 1419... 

A variety of other elemental arsenic forms have been synthesized in laboratories, including amorphous ( black ) elemental arsenic, various arsenic clusters, and even larger fullerene-like cage structures (Zhao et al., 2004 Baruah et al., 2004). The compositions of the clusters are As , where n = 1—5. AS4 or yellow arsenic is the most common form of elemental arsenic in the vapor phase and the bond length between the arsenic atoms in AS4 is about 2.435 A (Zhao et al., 2004 Karttunen, Linnolahti and Pakkanen, 2007), 913. 

Horesh, M. Y. (2001). Geochemical investigation of a high arsenic cluster, Northport, Maine, U.S.A. M.S. thesis, University of Maine, Orono, Maine. 

There have been many studies of the crystalline structures of elemental phosphorus [10,45], and the microscopic structures of the amorphous modifications (red, black, grey vitreous) are still the subjects of considerable attention. Gas phase clusters have been of interest for many years, and Martin [19] has detected mass spectroscopically clusters up to > 6000. Nevertheless, little experimental information was available until recently on the structure of clusters with > 4, and this is also true for arsenic clustere, As . 

A series of alkali metal and alkaline earth metal-arsenic clusters formulated as M[c-Ass] (M = Li, Na, K, Rb, Cs) andM [c-Ass]+(M = Be, Mg, Ca, Sr, Ba) were investigated by Xu and Jin [173] using DFT methods. All M[c-Assj andM [c-Ass]" clusters adopt a pentagonal pyramidal structure with Csv symmetry, its basal plane involving the planar pentagonal [c-Ass] anion. From molecular orbital and NICS analysis, it was established that each of these species had three delocalized n MOs that satisfied the 4h - - 2 electron counting rule and therefore exhibit n-aromatic character. 

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