Synthesis and Characterization of 3-Chloropropyl-substituted o-Carboranes: Crystal Structures of 1,2-(1,3-Propanediyl)-o-carborane, 1-(3-Chloropropyl)-o-carborane and 1,2-Bis(3-chloropropyl)-o-carborane

The reactions of the lithio-o-carborane Li2C2B10H10 with ClCH2CH2CH2Br were studied under various conditions. While the main product is the known exo-polyhedrally cyclized 1,2(1,3-propanediyl)-o-carborane (2), the expected 3-chloropropyl-substituted carborane products 1(ClCH2CH2CH2)C2B10H11 (3) and 1,2-(ClCH2CH2CH2)2C2B10H10 (4) can be obtained in a total yield of 22%. In the presence of CuCl, the same reaction proceeded rather slowly and gave compound 3 and bis(o-carborane) (5) in small yields, with the recovery of the starting o-C2B10H12. Compounds 2 – 4 were characterized by means of IR and NMR spectroscopy and mass spectrometry, as well as by single-crystal X-ray diffraction.