Addition of polysubstituted alkenes, aromatic alkynes, and dienes to a metal-stabilized thiyl radical via carbon-sulfur bond formation: Electrochemical, chemical, and computational investigations

作者：Sampson Kagna Ouch; Kumar Davinder; Mashuta Mark S; Grapperhaus Craig A^*

来源：Inorganica Chimica Acta, 2013, 408: 1-8.

DOI：10.1016/j.ica.2013.08.003

• Metal-stabilized thiyl radicals
• C-S bond formation
• Electrochemistry
• Alkenes
• Alkynes
• Dienes

The addition of polysubstituted alkenes, alkynes, and dienes to the metal-stabilized thiyl radical complex [Ru-1](+) was evaluated by electrochemical, chemical, and computational methods. The [Ru-1](+) radical complex was generated by two successive one-electron oxidations of the metal thiolate precursor PPN[Ru(DPPBT)(3)], PPN[Ru-1], (PPN = bis(triphenylphosphine) iminium; DPPBT = diphenylphosphine-benzenethiolato). Rate constants were experimentally determined by cyclic voltammetric methods over multiple scan rates using [Ru-1] solutions containing unsaturated substrates. Rate constants for polysubstituted alkenes range from 1.1 x 10(1) to 8.8 x 10(2) M-1 s(-1,) which are at 3-5 orders of magnitude slower than their monosubstituted counterparts. Rate constants are slower for substituted alkynes varying from 2.3 x 10(2) to 1.2 x 10(4) M-1 s(-1), which are similar to 100 times slower than the corresponding alkenes. Selected complexes were spectroscopically characterized following synthesis by chemical oxidation methods. Addition of asymmetrically substituted alkenes and alkynes yield [Ru-1 .substrate](+) products as a mixture of isomers, which were assigned based on P-31 NMR and density functional theory calculations (B3LYP/LANL2DZ + 6-31 g). The solid state structure of [Ru-1 .cyclohexene]PF6 was determined by single crystal X-ray diffraction.

• 出版日期2013-11-1