Synthesis, Structural Characterization and Reactivity of Twelve-, Thirteen-, and Fourteen-Vertex Carboranes

This thesis focused on the synthesis, structural characterization and reaction chemistry of supercarboranes. Several 13- and 14-vertex carboranes were synthesized and characterized using polyhedron expansion methodology, which includes CAp species such as 1,12-bis(trimethylsilyl)-1,12-C2B11H11, 2,9-bis(trimethylsilyl)-2,9- C2B12H12, 2,9-C2B12H14 and 2,2'-bis(2,9-C2B12H13). Subsequently, several CAd 14-vertex germa-, stanna-, and plumba-carboranes of the MC2B11 system, CAp 14-vertex ruthenacarboranes and CAd 15-vertex ruthenacarborane were synthesized and structurally characterized via salt metathesis reactions of carborane dianions with metal halides.;Reactivity of 14-vertex carboranes were studied. They reacted with nucleophiles to give nido-C2B12, nido-C2B11 and closo-CB11 carborane anions dependent upon the nature of nucleophiles. Electrophilic substitution reaction of 14-vertex carborane afforded multi-substituted species. Reaction of C,C'-linked 13-vertex carboranes with tBuOK or NaH in dry THF at room temperature gave 13-vertex carborane monoanions with substantial double-bond character between the cage carbon atom and the exo vicinal carbon atom. These monoanions represent the first examples of 13-vertex carboranes with exo-th-bonding to hypercarbon atoms. Treatment of CAd 13-vertex carboranes with bulky NHCs afforded a series of 1:1 13-vertex nido III carborane-carbene adducts. On the other hand, reaction of CAp 13-vertex carborane 1,12-bis(trimethylsilyl)-1,12-C2B11H11 with NHCs generated cage boron extrusion products.