Synthesis and Study of Derivatives of the [B10H10]2– Anion with Amino Acids

The interaction between tetrahydrofuran, tetrahydropyran, and 1,4-dioxane derivatives of the [B10H10]2– anion and a number of amino acids (glycine, cysteine, serine, and p-aminobenzoic acid) has been studied. It has been shown that, during the reactions, the exo-polyhedral cyclic substituent is opened to form closo-decaborates containing the pendant amino acid group, while the nucleophilic reagent is attached via the oxygen atom. The nucleophilic reagents can be both amino acids (in water) and their sodium salts (in dimethylformamide). All the compounds obtained are effective polydentate ligands capable to be coordinated to the metal through the donor atoms of the amino acid moiety attached and by forming three-center two-electron bonds. The synthesized compounds have been studied by elemental analysis, IR spectroscopy, 11B, 13C, and 1H NMR spectroscopies, and ESI mass spectrometry. closo-Decaborates with pendant amino acid moieties are of interest for 10B neutron capture therapy of malignant tumors due to the high content of boron atoms and a convenient way to transport them to the cells affected.