Synthesis of [B12H12]2− based extractants and their application for the treatment of nuclear wastes

Several closo-hydroborates bearing phosphite oxide, phosphine oxide or CMPO (carbamoylmethylphosphine oxide) groups, Cs[(Ph2P(O))2N(H)B12H11] (1), K[Ph2P(O)CH2C(O)N(H)2B12H11] (2), Na[Bz2N(H)B12H10OCH2CH2OCH2CH2P(O)(OBu)2] (5), Na[Bz2N(H)B12H10O(CH2)4N(R)C(O)CH2P(O)(Ph)2] (9, R=Pri; 10, R= Octyl), Na[Bz2N(H)B12H10OCH2CH2OCH2CH2N(Bui)C(O)CH2P(O)(Ph)2]− (11) were synthesised employing novel neutral bipolar intermediates [Bz2N(H)B12H10O(CH2)4] (3) and [Bz2N(H)B12H10O(CH2CH2)2O] (4) as useful synthons. All new compounds were characterised by NMR spectroscopy and mass spectrometry techniques. Their abilities to extract selectively the radionuclides 241Am and 152Eu from nuclear waste solutions were investigated using a liquid–liquid extraction technique. Promising results were obtained with compound 10, which exhibits enhanced hydrophobicity and solubility in organic extraction solvent.