Similarity selenium

Complexes of both selenium(IV) and tellurium(IV) with sulfur-containing ligands are known although the structural properties appear to have been determined only for the tellurium(IV) species. However, due to the smaller size of selenium(IV) and its poorer acceptor properties, as compared with tellurium(IV), its maximum coordination number appears to be six whilst it has been found to be eight for tellurium.78 Furthermore, the greater tendency of tellurium to form secondary bonds may cause the structures of similar selenium(IV) and tellurium(IV) compounds to be different. 9 It is also pertinent to note that the reduction of tellurium(IV) to... 

Similar selenium-catalysed syntheses of 5-alkyl thiocarbamates [184]... 

A similar selenium insertion proceeds with lithium amides of secondary amines. In the presence of an isocyanide, lithium selenocarbamidates 2 are produced, which can be trapped with butyl iodide to give the corresponding iso-selenoureas 3 in good yields (Scheme 3) [5]. When the reaction is carried out under carbon monoxide atmosphere, the corresponding selenocarbamates are obtained [5]. 

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