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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-CB₉H_9-nX_n]^- and [1-Ph-closo-1-CB₁₁H_11-nX_n]^- 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.

Keywords: Boranes; Carboranes; Monocarbaboranes; Brellochs Reaction; Aldehydes; Rearrangements; Arenes; Cluster-closure reactions.

References: 53 live references.