Dialkyl Chloronium Ions

摘要

Halonium ions (R_2X~+) are well-recognized reactive intermediates in electrophilic chemistry. Because their stabilities increase down the halogen group, iodonium salts are commonly used reagents. Halonium ions in which R is a stabilizing aryl substituent have been isolated and structurally characterized for X = Cl, Br, I. With trialkylsilyl substituents, bridging fluorides with potential fluoronium ion character are also stable. However, the existence of simple dialkylhalonium ions such as (CH_3)_2X~+ has only been determined spectroscopically, and the potential utility of the lighter element ions (e.g., X = Cl) as reagents is not well explored because they are stable only at low temperatures in synthetically challenging superacid media. Gas-phase dialkylhalonium ion chemistry has received more attention.