Generation of an Organotellurium(II) Cation

Abstract

We expected that the chemical trapping products of low‐coordinated tellurenyl cation species can also be kinetically stabilized by the Tbt or Bbt group. Recently, we have reported the halogenation reactions of Bbt‐substituted ditelluride, BbtTeTeBbt, leading to the formation of the TeII–TeIV mixed‐valent tellurenyl fluoride, BbtTeTe(F)2Bbt, and tellurenyl halides, BbtTeX (X = Cl, Br, I). During the dehalogenation reactions of these tellurium halides, it is rational to postulate the formation of a tellurenyl cation species as an intermediate. In this paper, we report the successful trapping of tellurenyl cation species with butadienes or triphenylphosphane, and the regeneration of the tellurenyl cation species by thermal retro [1+4] cycloaddition of the diene adducts.

Tellurium: a maverick among the chalcogens

“…The monohalides RTeX can also be stabilised (a) by the use of highly bulky groups (kinetic stabilisation) or (b) via intramolecular coordination of a heteroatom substituent attached to an aryl ring (thermodynamic stabilisation) (Scheme 6). 46 For example, stoichiometric reactions of SO 2 Cl 2 , Br 2 or I 2 with the bulky aryl ditelluride BbtTe-TeBbt (Bbt = 2,6-[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl) produces aryltellurium(II) halides BbtTeX (X = Cl, Br, I) which can be isolated as red-purple, blue or green solids, respectively. 46 Interestingly, halogenation of ditellurides with less bulky aryl substituents generates mixed-valent ditellurium dihalides ArX 2 Te IV -Te II Ar (Ar = 2,6-dimesitylphenyl) (Section 1).…”

“…46 For example, stoichiometric reactions of SO 2 Cl 2 , Br 2 or I 2 with the bulky aryl ditelluride BbtTe-TeBbt (Bbt = 2,6-[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl) produces aryltellurium(II) halides BbtTeX (X = Cl, Br, I) which can be isolated as red-purple, blue or green solids, respectively. 46 Interestingly, halogenation of ditellurides with less bulky aryl substituents generates mixed-valent ditellurium dihalides ArX 2 Te IV -Te II Ar (Ar = 2,6-dimesitylphenyl) (Section 1). 5 The latter can be used as a source of aryltellurenyl cations stabilised by two-electron donors, e.g.…”

“…5 The latter can be used as a source of aryltellurenyl cations stabilised by two-electron donors, e.g. PPh 3 (41), NHC (42) (Scheme 18), 46,47 or via [1+4] cycloaddition with 2,3-dimethyl-1,3-butadiene. 46…”

“…PPh 3 (41), NHC (42) (Scheme 18), 46,47 or via [1+4] cycloaddition with 2,3-dimethyl-1,3-butadiene. 46…”

Organophosphorus–Tellurium Chemistry: From Fundamentals to Applications

“…13 As illustrated in Figure 2, the crystal structure of BaP 4 47 The 1 J( 31 P, 125 Te) coupling of 1387 Hz reported for 9a 48 is significantly higher than those for other aryltellurenyl cations.…”