Synthesis of Perhalogenated Monohydroxy Derivatives of the closo-Decaborate Anion [2-B10X9OH]2– (X = Cl, Br)

An efficient two-stage method has been developed for the synthesis of perhalogenated monohydroxy derivatives of the closo-decaborate anion with the composition [2-B10X9OH]2– (X = Cl, Br). The method involves complete halogenation of the boron cage in the initial DMF-containing derivative [2‑B10H9OCHNMe2]– by its reaction with sulfuryl chloride (SO2Cl2) or elemental bromine (Br2), followed by hydrolysis of the obtained perhalogenated derivatives [2-B10X9OCHNMe2]– (X = Cl, Br) with hydrazine monohydrate (N2H4·H2O). This synthetic approach allows for the production of the target compounds with high yield (80–85%) and high purity, as confirmed by a range of physicochemical analysis methods, including multinuclear 11B, 1H, and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. The structures of the [2-B10X9OCHNMe2]– and [2-B10X9OH]2– anions were determined by single-crystal X-ray diffraction analysis.