The standard enthalpies of formation of 1- and 2-Adamantyl cations and radicals. An ab initio study

Abstract

The results of a G2(MP2) computational study involving 1- and 2-Adamantyl cations ( 1 +, 2 + ) as well as 1- and 2-Adamantyl radicals ( 1 , 2 ) are presented. They provide purely computational thermodynamic data for the following processes: (i) Ionization of 1 and 2 , (ii) Exchange of hydrogen atoms or hydride anions between Adamantyl radicals or cations and alkyl radicals or cations, respectively. These data, once combined with the experimental enthalpies of formation of iso -C 3 H 7 ,iso -C 3 H 7 + ,tert -C 4 H 9 and tert -C 4 H 9 + , allowed us to screen the available experimental data and to define a self-consistent set of experimentally-based standard enthalpies of formation, Δ f H 0 m , for Adamantyl species, namely: Δ f H 0 m ( 1 +, g)=162.0±2.0 ; Δ f H 0 m ( 2 +, g)=171.9±2.0 ; Δ f H 0 m ( 1 , g)=17.9±2.1 , Δ f H 0 m ( 2 , g)=16.6±2.0 kcal mol −1 .