Polychalcogenide synthesis

Heavy ketones have been synthesized by several synthetic methods shown in Scheme 19 (i) the reaction of divalent group 14 element species with chalcogen sources, (ii) the reaction of dihydrometallanes with chalcogen sources, (iii) the dechalcogenation of metal polychalcogenides, (iv) the reaction of dilithiomet-allanes with dihalochalcogenides, and (v) substitution of the chloro group of heavy acyl chlorides. The methods used for the synthesis of heavy ketones are summarized in Tables 3-5. 

The hydrothermal method has been employed in recent years to synthesize a variety of solids that include aluminium phosphates (ALPOs) and other microporous transition-metal phosphates and transition-metal polychalcogenides (Davis Lobo, 1992 Haushalter Mundi, 1992 Liao Kanatzidis, 1990, 1992). Unlike zeolites, synthesis of ALPOs requires acidic or mildly basic conditions and no alkali metal cations. A typical synthetic mixture for making ALPO consists of alumina, H3PO4, water and an organic material such as a quaternary ammonium salt or an amine. The hydrothermal reaction occurs around 373-573 K. The use of fluoride ions, instead of hydroxide ions as mineralizer, allows synthesis of novel microporous materials under acidic conditions (Estermann et al, 1991 Ferey et ai, 1994). 

Kanatzidis, Mercouri G. and Sutorik, Anthony C., The Application of Polychalcogenide Salts to the Exploratory Synthesis of Solid-State... 

Several approaches have been used for the synthesis of metal carbonyl polychalcogenide anions.28-31... 

Hydro(solvo) thermal technique, synthesis of metal-carbonyl polychalcogenide anions, 250-252... 

It is believed that the identity and concentration of the mineralizer is the single most important factor in inorganic synthesis in supercritical fluids. Generally the most effective mineralizers are small nucleophiles such as OH , halides, sulfides and polychalcogenides, and carbonates and bicarbonates. Normally these are added as alkali metal salts but often ammonium salts are used as well. It is our qualitative experience that ammonium salts, when feasible, are superior to alkali metal cations. 

In most cases, the starting materials used for solvothermal synthesis (as well as for normal reactions) are of simple composition e.g. binary metal halides, metal chalcogenides or polychalcogenides and simple metal carbonyls). 

Polychalcogenides have also attracted much attention in cluster synthesis, due to the unique coordination modes adopted by these ligands." Often denoted 4 , polychalcogenides are known to exist in solution as a complex mixture of soluble anions, where x = 2-6." ... 

It appears that hydrothermal synthesis of polychalcogenide compounds is not only feasible but also a promising new alternative to the more traditional techniques usually employed in this area of chemistry. It may yield structurally and chemically unique compounds not accessible otherwise. 

Molten alkali-metal polyselenide fluxes also prove to be useful in the syntheses of unusual quaternaries, here illustrated by the synthesis of the onedimensional polyselenide K3CuNb2Sei2-Both of these polychalcogenides are synthesized at 870° or above. The use of low temperatures (< 450°) is not a necessary condition for the synthesis of metal polychalcogenides, as has been implied. ... 

SYNTHESIS OF TERNARY CHALCOGENIDES IN MOLTEN POLYCHALCOGENIDE SALTS a-KCuQ, KAuS NaBiS, KFeQ (Q = S, Se)... 

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