Polyhedral azadicarbaborane chemistry. The ‘converse’ synthesis of a small family of 6,9-(NHR)-bridged-arachno-5,10-dicarbadecaboranes

Addition of PhCCH to hypho-type species [(R′H2N)B8H11NHR] proceeds readily with the displacement of R′NH2 to give corresponding N-bridged arachno ten-vertex species [6,9-μ-(NHR)-5-Ph-arachno-5,10-C2B8H10] (15–34%), for which DFT structural and GIAO 11B nuclear shielding calculations suggest the syn configurations that have the R and Ph groupings on the same side of the molecule.