Exchange polarization effects in the interaction of closed-shell systems

1977 ◽  
Vol 46 (4) ◽  
pp. 277-290 ◽  
Author(s):  
Grzegorz Chałasiński ◽  
Bogumił Jeziorski
Keyword(s):  
Closed Shell ◽  
Polarization Effects ◽  
Exchange Polarization

On the exchange polarization effects in the interaction of two helium atoms

1976 ◽  
Vol 32 (1) ◽  
pp. 81-91 ◽  
Author(s):  
Grzegorz Chałasi[ngrave]ski ◽  
Bogumił Jeziorski
Keyword(s):  
Polarization Effects ◽  
Helium Atoms ◽  
Exchange Polarization

Enhanced polarization effects in chiral composites

1994 ◽  
Vol 4 (12) ◽  
pp. 2601-2607 ◽  
Author(s):  
A. H. Sihvola
Keyword(s):  
Polarization Effects

Hydrostibination of Alkynes: A Radical Mechanism

2020 ◽  
Author(s):  
Josh MacMillan ◽  
Katherine Marczenko ◽  
Erin Johnson ◽  
Saurabh Chitnis
Keyword(s):  
Density Functional ◽  
Activation Barrier ◽  
Closed Shell ◽  
Reaction Rates ◽  
Radical Mechanism ◽  
Neutral Radical ◽  
Kinetic Isotope ◽  
Rate Limiting Step ◽  
Ionic Mechanisms ◽  
Terminal Acetylenes

The addition of Sb-H bonds to alkynes was reported recently as a new hydroelementation reaction that exclusively yields anti-Markovnikov <i>Z</i>-olefins from terminal acetylenes. We examine four possible mechanisms that are consistent with the observed stereochemical and regiochemical outcomes. A comprehensive analysis of solvent, substituent, isotope, additive, and temperature effects on hydrostibination reaction rates definitively refutes three ionic mechanisms involving closed-shell charged intermediates. Instead the data support a fourth pathway featuring neutral radical Sb<sup>II</sup> and Sb<sup>III</sup> intermediates. Density Functional Theory (DFT) calculations are consistent this model, predicting an activation barrier that is within 1 kcal mol<sup>-1</sup> of the experimental value (Eyring analysis) and a rate limiting step that is congruent with experimental kinetic isotope effect. We therefore conclude that hydrostibination of arylacetylenes is initiated by the generation of stibinyl radicals, which then participate in a cycle featuring Sb<sup>II</sup> and Sb<sup>III</sup> intermediates to yield the observed <i>Z</i>-olefins as products. This mechanistic understanding will enable rational evolution of hydrostibination as a methodology for accessing challenging products such as <i>E</i>-olefins.

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