Tellurium bonding

Metal-Sulfur, -Selenium, and -Tellurium Bond Lengths, M—E—C Angles, and Torsion Angles for Three-Coordinate Aluminum, Gallium, and Indium Thiolates, Selenolates and Tellurolates", and Related Compounds... 

The vinylic carbon-tellurium bond in 3-129 can easily be cleaved by a tributyltin radical to afford vinyl radical 3-131, which can undergo further transformations as hydrogenation or C-C-bond formation, for example with dimethylfumarate in a (Z)-selective mode. 

The transformation of a carbon-tellurium bond into a carbon-halogen bond has been achieved in several types of organotellurium compound. 

The formation of the stylbenes, only in low yield, clearly shows that the fission of a vinyl tellurium bond is favourable towards the Ph-Te bond. 

Chemistry of compounds with silicon-sulphur, silicon-selenium and silicon-tellurium bonds... 

Aluminum(III)—sulfur—tellurium bonds, covalent and non-covalent, 9, 257... 

Manganese-sulfur bonds, in Mg carbonyls, 5, 770-771 Manganese-tellurium bonds, in Mg carbonyls, 5,... 

The preparation of 17o clearly showed that even stable compounds with lanthanide-tellurium bonds are easily accessible using this method. All three complexes exhibit strongly temperature-dependent HNMR spectra, which have been discussed in detail [47], The molecular structures of both 15o and 16o (Fig. 6) have been determined by X-ray diffraction [46, 47]. 

The platinum metal chalcogenides in general are easier to prepare than the corresponding oxides. Whereas special conditions of temperature and pressure are required to prepare many of the oxides, the platinum metals react most readily with S, Se, and Te. A number of additional differences concerning the chemistry of the chalcogenides and the oxides are summarized as follows The metal—sulfur (selenium, tellurium) bond has considerably more covalent character than the metal-oxygen bond and, therefore, there are important differences in the structure types of the compounds formed. Whereas there may be considerable similarity between oxides and fluorides, the structural chemistry of the sulfides tends to be more closely related to that of the chlorides. The latter compounds... 

A r/i3-carbon-tellurium bond can be homolyticaly cleaved either by action of a radical initiator (process A) or by light irradiation or heat (process B) (Scheme 82). The radical species formed interact with organic substrates through radical mechanistic pathways leading to the products with or without incorporation of tellurium in the final structure. 

Triphenylphosphane diphenylphosphinimide combined with tellurium in benzene to form a telluride with tellurium bonded to the phosphorus atom that was trivalent in the starting material4. 

One carbon-tellurium bond in divinyl tellurium is cleaved when the compound is treated in liquid ammonia with two molar equivalents of lithium5 7 or sodium8. The alkali ethenetellurolate was subsequently alkylated. 

The precipitation of black tellurium frequently encountered in reactions carried out with tellurols or tellurolates indicates that the carbon-tellurium bond is prone to cleavage under rather mild conditions. Alkanetellurols and -tellurolates appear to be less stable than the aromatic compounds. Exposure of tellurolates to air and water causes at least partial decomposition of arenetellurolates7 and ethynetellurolates8 to elemental tellurium. 

The aryl-tellurium bond in bromomagnesium benzenetellurolate is cleaved during its reaction with trimethylsilyl chloride, because bis[trimethylsilyl tellurium was observed as a reaction product1. 

When sodium benzenetellurolate was treated with sodium in liquid ammonia, the carbon-tellurium bond was cleaved. Benzene was isolated after work-up2. 

The P —Te and As —Te bonds were not attacked by water5,6 or methanol5. Trimethyl-stannane similarly cleaved the group V element-tellurium bonds in these compounds5 and in their coordination compounds with chromium and molybdenum carbonyls7. 

Te-NMR spectroscopic investigations ascertained the presence of the isomeric ketonyl tellurium trichlorides in the reaction mixtures. The isomers with tellurium on the less hindered carbon atom are generally the predominant species. Only 2-butanone yielded the 2-oxo-3-butyl tellurium trichloride as the major compound1, in which the tellurium is bonded to the more hindered carbon atom. Morgan2 claimed this compound to be 2-oxo-l-butyl tellurium trichloride. The symmetrical diketonyl tellurium dichlorides with tellurium bonded to the least hindered carbon were the only dichlorides detected1. 

The carbon-tellurium bond linking tellurium to the perfluoroalkyl groups in perfluoroalkyl telluriums is cleaved by potassium hydroxide liberating fluorohydrocarbons3. 

Phenyl tellurium trihalides react with linear olefins and cycloalkenes in methanol or other alcohols. In contrast to reactions in inert organic solvents, in alcoholic media the intermediate adduct between the olefin and the positive phenyldihalotelluro group is attacked by the alcohol and not by the halide ion. Therefore, the product is a 2-alkoxyalkyl phenyl tellurium dihalide. The reactions are regiospecific (tellurium bonding to the less hindered carbon atom) and highly stereospecific (anti-addition). 

Formation of Carbon-Sulfur, Carbon-Selenium and Carbon-Tellurium Bonds via Organomagnesium Compounds... 

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