Tellurocarbonyl compounds

The most straightforward route to heteroaldehyde and heteroketone complexes is the substitution of a heterocarbonyl compound for another coordinated ligand. This method is naturally restricted to heteroaldehydes and heteroketones stable in the uncoordinated form, i.e., is usually restricted to thioketones and a few stable seleno- and tellurocarbonyl compounds.141718,27118 In most cases, metal carbonyls or solvent complexes of metal carbonyls were used as the complex precursors. The photochemically or thermally induced loss of the ligand to be replaced is followed by coordination of the heterocarbonyl compound [Eq. (3)]. 

Tellurocarbonyl compounds, formed from aldehydes or ketones and bis[dimethylalumino] tellurium in refluxing dioxane, added to conjugated dienes to give cyclic tellurium compounds in good yields1. 

The organotelluride salt (28) readily dehalogenates a variety of a-halocarbonyl compounds, including ketones, acids and esters. It is not clear whether the first step is displacement of halide to afford an a-tellurocarbonyl compound, followed by attack upon the latter by (28), or whether (28) attacks the a-sub-stituent directly. Reduction can be effected by NaBH4 containing a catalytic quantity of (28). ... 

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