A CONVENIENT ROUTE TO CARBON-SUBSTITUTED DERIVATIVES OF NIDO-5,6-C2B8H12

An alternative route to the parent nido-5,6-C2B8H12 dicarbaborane is r eported together with a convenient synthesis of its carbon-substituted derivatives. The method is based on reactions between 4-(Me2S)-arachn o-B9H13 and alkynes (RRC2)-R-1-C-2 (where (RR2)-R-1 = H,H; Me, Me; Ph, H, and Ph,Ph) in toluene at reflux. The characteristic reaction mode i s a dicarbon insertion into the 9-vertex arachno cluster to produce a series of the 5,6-(RR2)-R-1-nido-5,6-C2B8H10 species combined with con comitant elimination of one {BH} vertex. The products were characteris ed by high-field H-1 and B-11 NMR spectroscopy and mass spectrometry a ssociated with [B-11-B-11]-COSY and H-1{B-11(selective)} measurements that permitted complete assignments of all resonances to individual cl uster {BH} units. (C) 1998 Elsevier Science S.A.