Distinguishing conventional and distonic radical cations by using dimethyl diselenide

Area of Science:

• Chemical kinetics
• Mass spectrometry
• Organic chemistry

Background:

• Distinguishing between distonic and conventional radical cations is crucial in chemical analysis.
• Previous methods, like using dimethyl disulfide, have limitations in speed and exclusivity.
• A more effective reagent is needed to differentiate these isomeric ions.

Purpose of the Study:

• To evaluate dimethyl diselenide as a reagent for identifying distonic radical cations.
• To compare the reactivity of dimethyl diselenide with dimethyl disulfide.
• To differentiate between distonic and conventional radical cations using their distinct reactions with dimethyl diselenide.

Main Methods:

• Investigating the reaction of various radical cations with dimethyl diselenide.
• Comparing CH3Se abstraction by distonic ions with CH3S abstraction by dimethyl disulfide.
• Determining the ionization energy of dimethyl diselenide using bracketing experiments.

Main Results:

• Dimethyl diselenide readily abstracts CH3Se from most distonic radical cations.
• This reaction is faster and more exclusive than the analogous reaction with dimethyl disulfide.
• Acidic distonic ions protonate dimethyl diselenide, while conventional radical cations undergo electron transfer or remain unreactive.
• The determined ionization energy of dimethyl diselenide (7.9±0.1 eV) predicts facile electron transfer with many conventional radical cations.

Conclusions:

• Dimethyl diselenide is a superior reagent for identifying distonic radical cations.
• It enables clear differentiation between distonic and conventional radical cation isomers.
• The reagent's reactivity profile, including electron transfer potential, broadens its applicability in radical ion chemistry.