Exploring the reactivity of L-tellurocystine, Te-protected tellurocysteine conjugates and diorganodiselenides towards hydrogen peroxide: synthesis and molecular structure analysis

Abstract

The oxidation reaction of _L-tellurocystine, [Te₂{CH₂CH(NH₃⁺)COO⁻}₂] (4) with H₂O₂ in the presence of HBr resulted in the formation of cyclic, zwitterionic organotellurolate(IV) species, namely [Te⁻{CH₂CH(NH₃⁺)COO}(Br)₃] (5). The H₂O₂ oxidation of Te-protected tellurocysteine derivatives [RTe{CH₂CH(NH₂)COOH}] [R = C₆H₅ (6) and 4-MeC₆H₄ (7)] in the presence of HCl resulted in the formation of chlorotellurane species [(C₆H₅)Te{CH₂CH(NH₃⁺)COOH}(Cl)₂]Cl (8) and [(4-MeC₆H₅)Te{CH₂CH(NH₃⁺)COO}(Cl)]Cl (9), respectively. The oxidation reaction of diorganodiselenides R₂Se₂ [R = 4-MeC₆H₄ (10), R = 4-OMeC₆H₄ (11), R = 3,4-Me₂C₆H₃ (12) and R = 2,4,6-Me₃C₆H₂ (13)] with H₂O₂ afforded homoleptic diorganoselenones R₂SeO₂ [R = 4-MeC₆H₄ (14), R = 4-OMeC₆H₄ (15), R = 3,4-Me₂C₆H₃ (16) and R = 2,4,6-Me₃C₆H₂ (17)], respectively. The synthesized compounds were thoroughly characterized by multinuclear NMR (¹H, ¹³C, ¹²⁵Te/⁷⁷Se), FT-IR spectroscopy, ESI-MS and elemental analysis. The molecular structures of the compounds were determined by single crystal X-ray diffraction studies.