An ab initio study of some free-radical homolytic substitution reactions at sulfur, selenium and tellurium

Schiesser, Carl H.; Smart, Bruce A.

doi:10.1016/0040-4020(95)00263-8

Cited by 52 publications

(34 citation statements)

References 50 publications

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“…23,27e29 It is interesting to note that the 'attack angle' in 7 is calculated to be 164 at this level of theory, slightly larger than the 'ideal angle' of about 154 calculated using MP2/DZP for the degenerate reaction of methyl radical with methaneselenol. 28 The geometrical 'lateness' of transition state 7 (R¼Me) is consistent with the energy data provided in Table 1; at all levels of theory the ring closure of radical 6 is calculated to be endothermic. In addition, inclusion of electron correlation also appears to be important in arriving at satisfactory energy barriers.…”

Section: Methodssupporting

confidence: 71%

7-Selenabicyclo[2.2.1]heptane

et al. 2012

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a b s t r a c tAb initio and density functional theory (DFT) calculations predict that intramolecular homolytic substitution by alkyl radicals at the selenium atom in seleninates proceeds through smooth transition states in which the attacking and leaving radicals adopt a near collinear arrangement. When forming a fivemembered ring and the leaving radical is methyl, G3(MP2)-RAD calculations predict that this reaction proceeds with an activation energy (DE 1 z ) of 30.4 kJ mol . Homolytic addition to the phenyl group was found not to be competitive with substitution, with a calculated barrier of 57.6 kJ mol À1. This computational study provides insight into homolytic substitution chemistry involving seleninates.

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Section: Methodssupporting

confidence: 71%

7-Selenabicyclo[2.2.1]heptane

et al. 2012

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“…12). Although the existence of a trivalent tellurium radical intermediate is still a controversial issue, 26,42,43 the intermediate, if any, should locate very close in energy to the transition state. Therefore, the degenerative transfer of TERP proceeds virtually in a concerted manner, and the involvement of a long-lived intermediate that may cause unwanted side reactions is unlikely.…”

Section: Mechanismmentioning

confidence: 99%

Development of organotellurium‐mediated and organostibine‐mediated living radical polymerization reactions

Yamago

2005

J. Polym. Sci. A Polym. Chem.

176

103

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Organotelluriummediated living radical polymerizations (TERPs) and organostibinemediated living radical polymerizations (SBRPs) provide well-defined polymers with a variety of polar functional groups via degenerative chain-transfer polymerization. The high controllability of these polymerizations can be attributed to the rapid degenerative-transfer process between the polymer-end radicals and corresponding dormant species. The versatility of the methods allows the synthesis of AB diblock, ABA triblock, and ABC triblock copolymers by the successive addition of different monomers. This review summarizes the current status of TERP and SBRP.

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“…In the earliest such report, Ando and his research team reacted a C 60 -substituted benzotetrasilacyclohexene (41) with bromine under irradiation (Scheme 7) 36 Ando demonstrated that the photolysis of partially tert-butyl-substituted disilanes 45 in the presence of C 60 results in the formation of 1,16-adducts 46 in 54 -62% yield (Scheme 8) 37,38 . Interestingly, unusual adducts similar to 49 were obtained as by-products with disilanes having trimethylsilyl substituents (Scheme 9).…”

Section: Si Simentioning

confidence: 99%

“…The analogous transition states involving chalcogen are predicted to deviate slightly from collinearity, with typical Si -S TS , Si-Se TS and Si -Te TS separations of around 2.4, 2.5 and 2.6Å, respectively, depending on the level of theory 41 . Very recently, the mechanism of homolytic substitution by silyl, germyl and stannyl radicals at group 14 higher heteroatoms was investigated by ab initio calculations (Scheme 10).…”

Section: Theoretical Studiesmentioning

confidence: 99%