Tellurium compounds dimer

The ligand chemistry of heterocyclic tellurium compounds has been examined over several years.85 86-92 104-106 The study105 of the monomeric (6) and dimeric (7) complexes, which were obtained from the reaction of Na2PdCl4 and tellurophene and separated by their solubility differences in acetone and chloroform, is illustrative of the preparative chemistry and characterization techniques used in this area of chemistry. 

Irradiation of benzene solutions of 7e-aryl arenetellurocarboxylates with light from a mercury lamp generated radicals via homolytic cleavage of the Te—CO bond. The free radicals subsequently formed aldehydes, diorgano tellurium compounds, and diorgano ditellurium compounds via hydrogen abstraction, dimerization and elimination of tellurium, or dimerization -. The products of the photo-induced reaction of Te-4-methylphenyl 2-methylthiobenzene(tellurocarboxylate) are given as an example . ... 

Because of the lower stability of Se(IV) compounds as compared with their Te(IV) analogues (95UK527), the reaction of the disilyldiimine with SeCU ends up in phenanthro[9,10-c]-l,2,5-selenadiazole. 3,4-(2,4-Di-terr-butylbenzo)-l,2,5-telluradiazole 75 was obtained by a treatment of the tellurium diimide 76 with a lithium salt of tris(rerr-butyl)aniline. Dimer 77 is an intermediate in this reaction (96IC9). 

A similar protocol applied to 2,5-biscarboxymethyl-3,4-bis bromomethyl thiophene gives rise to a thiophene-tellurophene diannellated compound A, which is the first tellurium-containing diheteropentalene. It cannot be isolated since it gives a dimeric product B and the reduced compound... 

The reaction of nitroalkanes and dinitroalkanes with sodium hydrogen telluride gives nitrosoalkane dimers and olefins, respectively.96 The reduction of other nitrogenated species such as hydroxylamines, azides, nitroso, azo, and azoxy compounds can also be performed by using tellurium reagents.6,11,12... 

When methylene bis[tellurium trichloride] was shaken with an aqueous solution of potassium disulfite at low temperatures, a red-brown crystalline solid was formed that melted over the temperature range 50 to 102°. Elemental analyses suggested that the compound is methylene ditellurium5,s. Mass spectral and NMR data indicate a cyclic structure for the dimeric methylene ditellurium6. 

Diphenyl tellurium succinate and phthalate were found to be monomeric. Diphenyl tellurium phthalate prepared from diphenyl tellurium dichloride and sodium phthalate was claimed to be dimeric. Diphenyl tellurium oxide and propiolactones formed oligomeric compounds. ... 

The tungsten complex 509j leads to a dimer containing an M—M bond, 511 (2S6). The selenium and tellurium Iron carbonyl compounds (512)... 

Telluroaldehydes have been generated and trapped for the first time by the reaction of benzylidenetriphenylphosphorane with "activated" tellurium (a method analogous to that previously used to prepare selenoaldehydes) (Scheme 22).71 A wide range of reactive ylides have been converted into the adducts (118) by reaction with borane.72 On heating, (118) rearrange to triphenylphosphine-monoalkylborane adducts (119) which undergo the expected hydroboration reactions with alkenes. A new route to phosphaalkenes (121) is available from the reaction of phosphinomethylenetriphenylphosphoranes (120) with Lewis acids.73 In the case of (120, R2=NPr 2) the compounds (121) can be isolated and in one case an X-ray structure was obtained. However, similar reactions of (120, r2=Bu ) lead to the dimers (122). 

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