Synthesis and Applications of Perfunctionalized Boron Clusters
This Viewpoint Article describes major advances pertaining to perfunctionalized boron clusters in synthesis and their respective applications. The first portion of this work highlights key synthetic methods allowing one to access a wide range of polyhedral boranes (B 4 and B 6 -B 12 cluster cores) that contain exhaustively functionalized vertices. The second portion of this Viewpoint showcases the historical developments in using these molecules for applications ranging from materials science
... medicine. Lastly, we suggest potential new directions for these clusters as they apply to both synthetic methods and applications. Graphical abstract The present Viewpoint Article summarizes the syntheses and applications of perfunctionalized boron clusters with particular highlights on foundational works as well as the most up-to-date examples. We also provide a brief outlook on the field as it stands in the context of potential further development and application of boron cluster chemistry to solve pressing problems in chemistry, materials science and medicine. Homoperfunctionalized B 12 Clusters Halogenation-The first reported perfunctionalization of closo-[B 12 H 12 ] 2− involved direct perhalogenation with elemental chlorine, bromine and iodine, resulting in molecules of the type closo-[B 12 X 12 ] 2− (X = Cl, Br or I) that could be handled without decomposition under ambient conditions. 53 To avoid the use of chlorine gas, Ozerov and co-workers recently showed that perchlorination of closo-[B 12 H 12 ] 2− may be achieved using SO 2 Cl 2 as a chlorinating agent, leading to a more operationally simple synthesis. 65 Perfluorination of closo-[B 12 H 12 ] 2− proved more difficult and was first achieved by Solntsev and co-workers in the early 1990's through the action of supercritical HF at 550°C, producing Cs 2 [B 12 F 12 ] in 38 % yield. 66 Later, work by Strauss and co-workers described improved yields of closo-[B 12 F 12 ] 2− salts up to 74 % and could be carried out on multigram scale using nonspecialized glassware. 67, 68 Axtell et al.