Tellurium-Oxygen Bonds

With other substituted phenols, the tellurane structure was not significantly altered by the presence of strongly electron-withckawing substituents in the para position. Only strong steric hindrance led to a change in the structure and the length of the tellurium-oxygen bond. (Table 8.3)... 

Table 8.3 Length of the tellurium-oxygen bond in aryloxytelluranes...

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... 

Diaryl ditellurium compounds, when heated in pyridine, ethanol, or acetic acid with selenium dioxide, produced the corresponding bis[aryltelluro] selenium and derivatives of these compounds with oxygen bonded to tellurium and selenium4. 

Tellurium-oxygen system comprises a wide number of phases. Tellmium monoxide TeO probably exists only in the gas phase. No evidence of its existence in the solid state has been obtained. The He(I) photoelectron spectrum of the molecular beam that has been formed by heating Te02 in vacuo indicates that TeO is the dominant species in the vapor phase.Studies of the absorption and emission spectra of TeO(g) have yielded the bond dissosiation energy of263.2kJmoU. The Te=0 bond length of 1.828 A. is estimated from the rotational fine structme of the electronic absorption spectrum. 

Tellurium-oxygen secondary bonds (2.762 and 2.787 A) were found in dimeric 2,2 -biphenylene-2-biphenyltellurium 2,4,6-trichlorophenoxide [520]. 

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