Synthesis and characterization of water-soluble boron-substituted ortho-carborane derivatives

Abstract

Abstract The synthesis of water-soluble, boron-substituted carborane derivatives was achieved by treatment of boron-substituted bromoalkyl carborane derivatives with trimethylphosphine to yield the corresponding phosphonium salts. These new carborane salts exhibit solubility in both aqueous and polar organic media. Herein we report the synthesis and characterization of the first water-soluble, boron-substituted carborane species, closo-9,12-(CH2CH2CH2P(CH3)3+Br–)2-1,2-C2B10H10, 4, and closo-3-[CH2CH2CH2P(CH3)3+Br–]-1,2-C2B10H11, 5. The crystal structure of 5 is reported. Additionally, another method of preparing mono- and difunctionalized water-soluble phosphonium salts of B3-substituted carborane derivatives was developed. This method produces both the monophosphonium salt, closo-3-[CH2CH(CH2I)CH2P(CH3)3+I–]-1,2-C2B10H11, 8, and the diphosphonium salt, closo-3-[CH2CH(CH2P(CH3)3+I–)2]-1,2-C2B10H11, 9. © 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS synthesis / boron-substituted ortho-carboranes / phosphonium salts / water-soluble derivatives / X-ray crystallography