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-MeOC 6H 4COCH 2) 2TeBr 2

Abstract

Bis( p-substituted benzoylmethyl)tellurium dibromides, ( p-YC 6H 4COCH 2) 2TeBr 2, (Y=H ( 1a), Me ( 1b), MeO ( 1c)) can be prepared either by direct insertion of elemental Te across C Rf–Br bonds (where C Rf refers to α-carbon of a functionalized organic moiety) or by the oxidative addition of bromine to ( p-YC 6H 4COCH 2) 2Te (Y=H ( 2a), Me ( 2b), MeO ( 2c)). Bis( p-substituted benzoylmethyl)tellurium dichlorides, ( p-YC 6H 4COCH 2) 2TeCl 2 (Y=H ( 3a), Me ( 3b), MeO ( 3c)), are prepared by the reaction of the bis( p-substituted benzoylmethyl)tellurides 2a– c with SO 2Cl 2, whereas the corresponding diiodides ( p-YC 6H 4COCH 2) 2TeI 2 (Y=H ( 4a), Me ( 4b), MeO ( 4c)) can be obtained by the metathetical reaction of 1a– c with KI, or alternatively, by the oxidative addition of iodine to 2a– c. The reaction of 2a– c with allyl bromide affords the diorganotellurium dibromides 1a– c, rather than the expected triorganotelluronium bromides. Compounds 1– 4 were characterized by elemental analyses, IR spectroscopy, 1H, 13C and 125Te NMR spectroscopy (solution and solid-state) and in case of 1c also by X-ray crystallography. ( p-MeOC 6H 4COCH 2) 2TeBr 2 ( 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.