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Methyl and t-butyl esters of α-bromoacetic acid added oxidatively to elemental tellurium in the presence of sodium iodide to give high yields of crystalline bis(alkoxycarbonylmethyl)tellurium(IV) diiodides, (ROCOCH2)2TeI2. The chloro and bromo analogs were prepared via their reduction into tellurides followed by dihalogen oxidation. Activation of the α-Csp3–Br bond by ester functionality appears to be insufficient as methyl α-bromoacetate failed to add to Te(0) or aryltellurium(II) bromides. The nucleophilic substitution reaction of α-bromoesters with aryltellurolates, ArTe−Na+ (Ar = 1-C10H7, Np; 2,4,6-Me3C6H2, Mes), gave (alkoxycarbonylmethyl)aryltellurides that were characterized as mixed diorganotellurium dihalides. Crystal structures of Np(MeOCOCH2)TeBr2, Mes(MeOCOCH2)TeBr2 and Mes(t-BuOCOCH2)TeCl2 show that the functionalized organic moiety, ROCOCH2, behaves as a (C, O) chelating ligand. The carbonyl O atom of the ester group in these compounds is involved in a 1,4-Te⋯O secondary bonding interaction. However, the functionalized ligands in the case of (MeOCOCH2)2TeI2 are devoid of such an interaction. Surprisingly, one of the two organic ligands in (MeOCOCH2)2TeBr2 takes part in an intramolecular 1,4-Te⋯O interaction, the other appears to involve an intermolecular Te⋯O interaction to result in a one-dimensional array of molecules in the crystal lattice.

Chlorotelluration of terminal acetylenes, RCH CH ( R = Ph, 1 ; 4-MeC 6 H 4 , 2 ; t -Bu, 3 ) with aryltellurium trichlorides and TeCl 4 in refluxing toluene affords (2-chloro-2-organylvinyl)tellurium(IV) dichlorides, Ar[R(Cl)C CH]TeCl 2 (Ar = 1-C 10 H 7 , 1Aa – 3Aa ; 2,4,6-Me 3 C 6 H 2 , 1Ba–3Ba ; 4-MeOC 6 H 4 , 1Ca ) and [ t -Bu(Cl)C CH] 2 TeCl 2 , 3a respectively. These Te(IV) derivatives on reduction with Na 2 S 2 O 5 give the corresponding vinyltellurides as oils, except (2,4,6-Me 3 C 6 H 2 )[Ph(Cl)C CH]Te ( 1B ) which is a crystalline solid. The dibromides ( 1Ab – 3Ab , 1Bb – 3Bb , 3b ) and diiodides ( 1Ac – 3Ac , 1Bc – 3Bc , 1Cc ) were obtained by the oxidative addition of dihalogens to the tellurides. The stereochemistry of the products has been established with the help of X-ray diffraction studies of 1Aa , 1Ba , 1Bc , 1Cc , 3Aa , 3a and 1B . Intramolecular Te⋯Cl attractive interactions appear to favor the ( Z ) conformation adopted by the 2-chloro-2-organylvinyltellurium group irrespective of the steric demand of the aryl ligand of the Te(IV) electrophile and the terminal acetylene substituent. The intermolecular Te⋯X secondary bonding interactions give rise to dimeric units in the lattices of 1-naphthyl- and anisyltellurium(IV) derivatives, but are absent among the mesityl analogues, consistent with the larger steric requirement of the latter ligand.