Isolation of a Nonicosahedral Intermediate in the Isomerization of an Icosahedral Metallacarborane

摘要

The mechanism by which the icosahedral carboranes, their C-substituted derivatives, and their heteroatom analogues rearrange has been the subject of speculation since the 1,2- to 1,7-isomerization of closo-C_2B_(10)H_(12) was reported more than 30 years ago. A number of possible mechanisms have been proposed on the basis of both experimental observations (product distributions) and theoretical calculations. As far as we are aware, however, the high temperatures generally required for these isomerizations have so far precluded isolation of any intermediate species: the identification of such intermediates is clearly important for judging the relative merits of the various mechanistic proposals.