ABSTRACT: An overview of the syntheses, structures, and reactivity of the compounds formed by the incorporation of a number of d- and f-block metals into C2B4- and C2B9-carborane cages have been presented. In addition, the development of a safe, bench-scale preparation of the toxic and commercially unavailable polyhedral borane synthon, namely pentaborane(9), has also been described. Thus, this report discusses the latest developments leading to a systematic synthetic approach to a number of carborane precursors and the subsequent reaction chemistry in the formation of a number of “carbons-apart” metallacarboranes.