Synthesis and reactivity of para-substituted benzoylmethyltellurium(II and IV) compounds: observation of intermolecular C-H-O hydrogen bonding in the crystal structure of (p-MeOC6H4COCH2)2TeBr2

Bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC6H4COCH2)2TeBr2, (y=H (1a), Me (1b), MeO (1c)) can be preparedeither by direct insertion of elemental Te across CRf-Br bonds (where CRf refers to α-carbon of a functionalized organic moiety) or by the oxidative addition of bromine to (p-YC6H4COCH2)2Te (y = H (2a), Me (2b), MeO (2c)). Bis(p-substituted benzoylmethyl)tellurium dichlorides, (p-YC6H4COCH2)2TeCh (y = H (3a), Me (3b), MeO (3c)), are prepared by the reaction of the bis(p-substituted benzoylmethyl)tellurides 2a--c with S02Cl2, whereas the corresponding diiodides (p-YC6H4COCH2)2Teh (y = H(4a), Me (4b), MeO (4c)) can be obtained by the metathetical reaction of la--c with KI, or alternatively, by the oxidative addition ofiodine to 2a--c. The reaction of 2a--c with allyl bromide affords the diorganotellurium dibrornides la--c, rather than the expectedtriorganotelluronium bromides. Compounds 1-4 were characterized by elemental analyses, IR spectroscopy, 1H, l3C and 125TeNMR spectroscopy (solution and solid-state) and in case of Ie also by X-ray crystallography. (p-MeOC6H4COCH2)2TeBr2 (1c) provides, a rare example, among organotellurium compounds, of a supramolecular architecture, where C-H-O hydrogen bonds appear to be the non-covalent intermolecular associative force that dominates the crystal packing.