10-VERTEX POLYHEDRAL MONOHETEROBORANE CHEMISTRY - SYNTHESES, MOLECULAR-STRUCTURES, AND NUCLEAR-MAGNETIC-RESONANCE CHARACTERIZATION OF SOME 9-SUBSTITUTED 6-AZA-ARACHNO-DECABORANES AND 6-THIA-ARACHNO-DECABORANES

Reactions between nido-NB9H12 1 or nido-SB9H11 2 and Lewis bases L und er a variety of conditions gave two series of corresponding arachno co mpounds, exo-9-L-arachno-6-NB9H12 3 and exo-9-L-arachno-6-SB9H11 4 whe re L include NEt(3), quinoline, isoquinoline, pyridine, urotropine (ur o), MeCN, MeNC, PPh(3), NH3 and SMe(2). All these compounds were chara cterized by mass spectrometry together with B-11 and H-1 NMR spectrosc opy. In some cases, the endo analogues endo-9-L-arachno-6-EB(9)H(11), where E = NH 5 or S 6 have also been tentatively identified by NMR spe ctroscopy. Single-crystal X-ray diffraction studies have been carried out on an example of 3 (L = MeNC) and two examples of 4 (L = 1/2 uro o r MeNC).