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 -YC 6 H 4 COCH 2 ) 2 TeBr 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 6 H 4 COCH 2 ) 2 Te (Y=H ( 2a ), Me ( 2b ), MeO ( 2c )). Bis( p -substituted benzoylmethyl)tellurium dichlorides, ( p -YC 6 H 4 COCH 2 ) 2 TeCl 2 (Y=H ( 3a ), Me ( 3b ), MeO ( 3c )), are prepared by the reaction of the bis( p -substituted benzoylmethyl)tellurides 2a – c with SO 2 Cl 2 , whereas the corresponding diiodides ( p -YC 6 H 4 COCH 2 ) 2 TeI 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, 1 H, 13 C and 125 Te NMR spectroscopy (solution and solid-state) and in case of 1c also by X-ray crystallography. ( p -MeOC 6 H 4 COCH 2 ) 2 TeBr 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.