Bis(carboranes) and Their Derivatives

Abstract

The synthesis, structures and reactivities of bis(carboranes) and their derivatives are reviewed with particular emphasis on 1,1′-bis(ortho-carborane), 1, reflecting the fact that the largest body of published work relates to this species. Much of the reactivity of 1 can conveniently be discussed with respect to four topics; 1 as a κ2-ligand to transition-metals, 5-membered cyclic derivatives with non-metals, deboronation–metalation chemistry and reduction–metalation chemistry. Although at a simple level bis(carboranes) are no more than two carborane moieties bonded together their chemistry is not merely that of the individual units, and the review, therefore, highlights the unique ways in which the presence of one carborane as a substituent significantly modifies the reactivity of the other as well as describing how having two linked cages affords unique bonding possibilities. Where appropriate reference is made to the real and potential applications of bis(carboranes) reflecting contemporary emphasis in carborane chemistry generally.