The RS-.HSR Hydrogen Bond: acidities of alpha,omega-dithiols and electron affinities of their monoradicals.
Gas-phase acidities (deltaGo(acid)) have been measured for 1,2-ethanedithiol, 1,3-propanedithiol, and 1,4-butanedithiol, using a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Adiabatic electron affinities (EAs) of the thiolate monoradicals of these compounds were assigned from electron photodetachment spectra of their corresponding thiolate monoanions, acquired using a cw-ICR. The dithiols exhibit enhanced acidities (up to 8.7 kcal/mol in deltaGo(acid)) and greater EAs (up to 6.7 kcal/mol) than analogous monothiol species. These differences are attributed to an intramolecular RS-.HSR hydrogen bond in the thiolate anion. Considerations of the RO-.HOR hydrogen bond in monoanions of alpha,omega-diols and in the [CH(3)O-.HOCH(3)] complex anion suggest that the RS-.HSR hydrogen bond provides up to 9 kcal/mol extra stabilization.
Karty
J M
JM
Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.
Wu
Y
Y
Brauman
J I
JI
D004220:Disulfides / Q000737:chemistry; D005583:Fourier Analysis; D005609:Free Radicals / Q000737:chemistry; D006860:Hydrogen Bonding; D007700:Kinetics; D013058:Mass Spectrometry; D008623:Mercaptoethanol / Q000031:analogs & derivatives* / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013816:Thermodynamics; D013879:Thioredoxins / Q000737:chemistry
D004220:Disulfides; D005609:Free Radicals; D013438:Sulfhydryl Compounds; D013879:Thioredoxins; D008623:Mercaptoethanol; C031854:1,2-ethanedithiol