Synthesis and structural characterization of mono- and bisfunctional o-carboranes

Functionalized o-carboranes are interesting ligands for transition metals. Reaction of LiC2B10H11 with Me2NCH2CH2Cl in toluene afforded 1-Me2NCH2CH2-1,2-C2B10H11 ( 1). Treatment of 1 with 1 equiv. of n-BuLi gave [( Me2NCH2CH2)C2B10H10]Li([1]Li), which was a very useful synthon for the production of bisfunctional o-carboranes. Reaction of [ 1] Li with RCH2CH2Cl afforded 1-Me2NCH2CH2-2-RCH2CH2-1,2-C2B10H10 (R = Me2N ( 2), MeO (3)). 1 and 2 were also prepared from the reaction of Li2C2B10H10 with excess Me2NCH2CH2Cl. Treatment of [1] Li with excess MeI or allyl bromide gave the ionic salts, [1-Me3NCH2CH2-2-Me-1,2-C2B10H10][1] ( 4) and [1-Me2N(CH2=CHCH2) CH2CH2-2-(CH2=CHCH2)-1,2-C2B10H10][Br] (6), respectively. Interaction of [1]Li with 1 equiv. of allyl bromide afforded 1-Me2NCH2CH2-2-(CH2=CHCH2)-1,2-C2B10H10 (5). Treatment of [1] Li with excess dimethylfulvene afforded 1-Me2NCH2CH2-2-C5H5CMe2-1,2-C2B10H10 (7). Interaction of [1] Li with excess ethylene oxide afforded an unexpected product 1-HOCH2CH2-2-(CH2=CH)-1,2-C2B10H10 (8). 1 and 3 were conveniently converted into the corresponding deborated compounds, 7-Me2NHCH2CH2-7,8-C2B9H11 (9) and 7-Me2NHCH2CH2-8-MeOCH2CH2-7,8-C2B9H10 (10), respectively, in MeOH-MeOK solution. All of these compounds were characterized by various spectroscopic techniques and elemental analyses. The solid-state structures of 4 and 6-10 were confirmed by single-crystal X-ray analyses.