Reactions with metal tellurides

Reactions with metals produce selenides and tellurides as illustrated by the reactions... 

Considering that homogeneous precipitation of metal chalcogenides (mainly sulphides) by reaction between metal ions and dissolved chalcogen is well established, the main difference between this deposition and similar reactions seems to be that the products adhere to a substrate to give a visible fdm (in this case) rather than only precipitate. Whether this is connected with the redissolu-tion/redeposition process that occurs with the Sn-S system or has some other explanation is important. If the former, it may be limited to only those systems that behave similarly. Otherwise it is not unreasonable to expect that other metal sulphides and selenides (possibly also tellurides, although tellurium tends to be much less soluble, if at all, in such solvents) may be deposited as films in this manner. 

On the other hand, polytellurides only seem to oxidize metals to the +1 or +11 state. Reaction of equimolar amounts of Te4 with M(CO)6 results in disubstitution of CO forming a cu-complex (CO)4MTe4 (M = Cr (45), W (47)47). If an excess of metal carbonyl is used in the presence of poly-telluride anion, multinuclear products can be isolated and metal-metal bonds can also form, leading to clusters. Careful manipulation of reaction conditions and choice of the polychalcogenide anion used makes possible partial oxidation of the metal centers and cluster formation. The reaction of iron carbonyls with polytelluride anions can lead to a wide array of cluster compounds, the identities of which are controlled by the stoichiometries and compositions of the starting telluride anions. For instance, reaction of [Fe(CO)5] with Te2 leads to the formation of [Fe3(CO)9(ju.3-Te)]2 (48),48 whereas its reaction with increasing amounts... 

One common present day preparation of dialkyl mono-and ditellurides involves the reaction of alkyl halides with alkali metal tellurides that have been prepared in situ. The reactions are commonly carried out in aqueous or nonaqueous solutions. Solutions of sodimn in liquid ammonia also provide a useful media for the reduction of tellurium. ... 

Tin metal reacts with chlorine and bromine in the cold and with fluorine and iodine on heating to give tin (IV) tetrahalides. Sulfur and selenium react vigorously with tin on heating to give tin(II) or tin(IV) chalcogenides, depending on the mole ratio of the elements used reaction with tellurium only provides the tin (II) telluride. 

The reactions of iron carbonyls with diorgano tellurides deserve mention, for example the reaction of Fe3(CO),2 with PhjTe gives Ph2TeFe(CO>4, whilst several ruthenium-carbonyl complexes have been prepared from reactions between diphenyl telluride and alcoholic carbon monoxide-saturated solutions of ruthenium trichloride hydrate. Various other ruthenium-carbonyl complexes of diorgano teUurides, including di- and tri-substituted species, have also been described. The utility of diphenyl telluride in transition metal carbonyl chemistry has also been well illustrated during studies of manganese and rhenium compounds. 

Alkynyl(phenyl)iodonium salts have found synthetic application for the preparation of various substituted alkynes by the reaction with appropriate nucleophiles, such as enolate anions [980,981], selenide and telluride anions [982-984], dialkylphosphonate anions [985], benzotriazolate anion [986], imidazolate anion [987], N-functionalized amide anions [988-990] and transition metal complexes [991-993]. Scheme 3.291 shows several representative reactions the preparation of Ai-alkynyl carbamates 733 by alkynylation of carbamates 732 using alkynyliodonium triflates 731 [989], synthesis of ynamides 735 by the alkyny-lation/desilylation of tosylanilides 734 using trimethylsilylethynyl(phenyl)iodonium triflate [990] and the preparation of Ir(III) a-acetylide complex 737 by the alkynylation of Vaska s complex 736 [991]. 

The ability to control product formation, the reproducibility of results, and the relatively mild conditions under which the reactions proceed, have made cluster syntheses by this method very attractive. Furthermore, the starting materials are themselves readily prepared and easily stored and handled. This is especially valuable in metal telluride chemistry, in which suitable reagents for cluster syntheses are often unstable and must be generated in situ, leading to complex mixtures of reaction products. The use of the silylated tellurium reagents Te(TMS)2 and RTe-TMS has allowed access to a wealth of metal tellurium clusters with unique structures and properties. " ... 

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