Boron cluster science

Fast-forwarding to the present, I have selected a few examples of current research activity in boron cluster science that in one way or another build on the fundamental discoveries and bonding models of polyhedral borane structures that originated a half century ago with Lipscomb and his compatriots. While current publications in these areas may or may not explicitly acknowledge this original work, it is in fact the foundation upon which modem studies of polyhedral boranes and related clusters rest. 

Boranes, boron clusters, and in particular, carboranes are of special interest due to their unique properties that cannot be found in organic counterparts. These uniqne properties are based either on the element boron, due to its electron deficiency, or on the structnral featnre of the cluster compound. Borane clusters as a class of materials have a wide range of potential applications. This is not only due to their unique electronic and nuclear features the fields of application, to name but a few, range from materials science through medical applications to catalysis, which will be described in more detail below [13]. Carboranes can be applied as liquid crystals in electro-optical displays [14], non-linear optics [15], and ion-selective electrodes [16] in the materials science arena. If carboranes are vaporized and fired at high temperatures they create boron films that are applied in Tokamak reactors for nuclear fusion [17]. Boranes have furthermore found application in airbag propellant systems in cars [18], as the stationary phase in gas chromatography [19] and in metal ion extraction systems, for example, for nuclear waste [20]. In medical applications, boron neutron capture therapy (BNCT), a special field of anti-cancer therapy, is noteworthy. 

Figure 9.59 Cluster ion formation of a boron nitride/graphite mixture in a laser plasma. (J. S. Becker and ff. J. Dietze, Fresenius ). Anal. Chem., 359, 338(1997). Reproduced by permission of Springer Science and Business Media.)...

Fig. 8.19. LIEDI mass spectrum of A -hexylpyridinium tetrafluoroborate in methanol at a concentration of 0.1 pi ml" scanned over the m/z 50-800 range. The insets show the [QA] and [C3A2] cluster ions for comparison of the experimental and calculated isotopic patterns that are characteristic of one and two boron atoms, respectively. Reproduced from Ref. [116] with permission. Elsevier Science Publishers, 2007.

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