Assembly of diverse structural types of organotellurium compounds in the reactions of (4-MeO-C6H4)2TeO with pyridine carboxylic acids

The reactions of Ar2TeO (Ar = 4-MeO-C6H4) with 2-, 3- and 4-pyridine carboxylic acids (LH) afforded different organotelluroxane structural types depending on the stoichiometry of the reactants and the conditions of the reaction. Ar2Te(L)OH (1a–1c) are formed in a 1:1 reaction of Ar2TeO with LH in the presence of water. On the other hand a 1:2 reaction under anhydrous conditions leads to the formation of Ar2TeL2 (2a–2c). A 2:2 reaction under anhydrous conditions affords the ditelluroxanes Ar2Te(L)OTe(L)Ar2 (3a–3c) while tritelluroxanes Ar2Te(L)OTeAr2OTe(L)Ar2 (4a–4c) are formed in 3:2 reactions. Interestingly, 3a–3c are formed in the reaction of 2a–2c with Ar2TeO. The former can be hydrolyzed to 1a–1c while the latter upon reaction with Ar2TeO lead to the formation of the tritelluroxanes 4a–4c. Attempts to metalate 2a with PdCl2(MeCN)2 leads to a transfer of the carboxylate ligand to palladium affording Ar2TeCl2 and PdL2. X-ray crystal structures of representative examples of the family of 1, 2 and 3 reveal interesting supramolecular structures and the formation of a novel [TeO]2 structural unit. The latter results from intermolecular secondary Te⋯O interactions.