Search for charge-remote reactions of even-electron organic negative ions in the gas phase. Anions derived from disubstituted adamantanes

Abstract

The collision induced decompositions of 3-substituted adamantanecarboxylate anions have been studied with a view to uncover charge-remote fragmentations of the 3-substituent. The 3-substituent is chosen so that it cannot approach the anion site and therefore any fragmentations of that substituent should proceed independently of the charged centre. (i) Charge-remote radical losses are observed from a 3-CH(Et)₂ substituent [e.g. Et˙ and ˙CH(Et)₂ losses], but the classical Adams–Gross charge remote loss of an ethene plus dihydrogen is not observed. (ii) Charge-remote loss of MeOD is observed from a 3-C(CD₃)₂(OMe) substituent together with a number of charge-remote radical losses [e.g. Me˙, MeO˙ and ˙C(CD₃)₂(OMe)]. (iii) The 3-substituent C(CD₃)₂ (OCHO) undergoes charge-remote loss of HCO₂D for both the carboxylate anion and its corresponding cation, a neutral reaction analogous to both the McLafferty rearrangement of radical cations and the Norrish II diradical rearrangement of aliphatic ketones. (iv) The charge-remote radical losses of MeO˙ and ˙CO₂Me occur from a 3-CO₂Me substituent.