Polyhedral Monocarbaborane Chemistry. A Review of Recent Developments Among C-Aryl Monocarbaborane Systems

Abstract

The Brellochs Reactions, of nido-B10H14 with aromatic aldehydes to give [6-Ar-nido-6-CB9H11]- anions in high yield, now permits excellent entries into C-aryl monocarbaborane chemistry, which is reviewed. From [6-Ar-nido-6-CB9H11]-, one-step cluster-closure, cluster-Aufbau, or cluster-dismantling reactions yield [1-Ph-closo-1-CB11H11]-, [7-Ph-nido-7-CB10H12]-, [1-Ph-closo-1-CB9H9]-, [2-Ph-closo-2-CB9H9]-, [4-closo-4-PhCB8H8]- and [6-Ph-arachno-6-CB8H13]. Second-step reactions involving these products yield [2-Ph-closo-2-CB10H10]-, [6-Ph-nido-6-CB8H11], [1-Ph-closo-1-CB7H7]- and [4-Ph-closo-4-CB8H8]-, as well as alternative routes to [1-Ph-closo-1-CB11H11]- and [1-Ph-closo-1-CB9H9]-. This readier access to this extensive suite of C-aryl monocarbaboranes permits a readier examination of their derivative chemistry. Monohalogenated and poly-halogenated species [1-Ph-closo-1-CB9H9-nXn]- and [1-Ph-closo-1-CB11H11-nXn]- have been formed as well as (SMe2)-substituted {CB11} and {CB10} systems. Coupling reactions with para-substituted [XC6H4CB11H10X]- systems give rod-like anions, and with poly-iodinated [PhCB11H5I6]- and [PhCB9H4I5]- give the globular [PhCB11H5Ar5I]- and [PhCB9H4Ar4I]- anions. Additional interesting species include [PhCB11H10CH=CHCH3]-, [PhCB11H10SMe(CH2)4OH]- and [PhCB9H8-6-OH]-. A review with 49 references.