Synthesis of Perchlorinated Sulfonium Derivatives of closo-Decaborate Anion [2‑B10Cl9SR2]− (R = i‑C3H7, n‑C3H7, n‑C4H9, n‑C8H17, n‑C12H25, n‑C18H37, CH2Ph, and cyclo-S(CH2)4)

A method for obtaining perchlorinated di-S,S-substituted derivatives of the closo-decaborate anion with various alkyl groups has been developed: [B10Cl9SR2]− (R= i-C3H7, n-C3H7, n-C4H9, n-C8H17, n-C12H25, n-C18H37, CH2Ph, and cyclo-S­(CH2)4). The method is based on the preparation of the sulfonium-substituted anion [B10H9SR2]− by alkylation of the anion [B10H9SH]2– with bromoalkanes (i-C3H7Br, n-C3H7Br, n-C4H9Br, n-C8H17Br, n-C12H25Br, n-C18H37Br, PhCH2Br, and BrCH2(CH2)2CH2Br) followed by the cluster chlorination with sulfuryl chloride SO2Cl2 in acetonitrile. The process proceeds until the hydrogen atoms in the boron cluster are completely replaced with chlorine and completes within 60 h. It has been found that the melting point of salts ((C4H9)4N)­[B10Cl9SR2] (R= i-C3H7, n-C3H7, n-C4H9, n-C8H17, n-C12H25, and n-C18H37) strongly depends on the length of the hydrocarbon chain of the substituent R.