| Abstract
| - [R+ OC Cl-] ion pairs were generated in methanol/dichloroethane solutions, with R+ as the1-bicyclo[2.2.2]octyl, 1-adamantyl, or 3-homoadamantyl cation. Ion pairs were produced either by the directfragmentation of alkoxychlorocarbenes (ROCCl), with R = 1-bicyclo[2.2.2]octyl, 1-adamantyl, or 3-homoadamantyl, or by the ring expansion−fragmentation of R‘CH2OCCl, with R‘ = 1-norbornyl, 3-noradamantyl, or 1-adamantyl. Correlations of the [ROMe]/[RCl] product ratios as a function of the mole fractionof MeOH in dichloroethane showed that the homoadamantyl chloride ion pairs, produced by either thedirect or ring expansion−fragmentations, were identical, solvent- and anion-equilibrated, and precursorindependent. Laser flash photolysis experiments gave 20−30 ps as the time required for solvent equilibrationand precursor independence. Methanol/chloride selectivities of the (less-stable) 1-adamantyl chloride and1-bicyclo[2.2.2]octyl chloride ion pairs were not independent of their ROCCl or R‘CH2OCCl precursors.Computational studies provided transition states for the fragmentations and for the structures of the ionpairs.
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