The electrophilic substitution of icosahedral closo-1-SB11H11 with methyl iodide has resulted in two B-functionalized thiaboranes, 7,12-I2-2,3,4,5,6,8,9,10,11-(CH3)9-1-closo-SB11 and 7,8,12-I3-2,3,4,5,6,9,10,11-(CH3)8-closo-1-SB11, with the former being significantly predominant. These two icosahedral thiaboranes are the first cases of polysubstituted polyhedral boron clusters with another vertex that differs from B and C. Such polyfunctionalizations have increased the earlier observed thiaborane icosahedral barrier, not exhibiting any reactivity toward bases, unlike the parent thiaborane. The search for methylation pathways has revealed that the complete B11-methylation is impossible, like in the case of decaborane(14), where this seems to be a result of the positively charged upper parts of these two molecules.

Department of General and Inorganic Chemistry Faculty of Chemical Technology University of Pardubice Studentská 573 532 10 Pardubice Czech Republic

Institute of Inorganic Chemistry Czech Academy of Sciences 250 68 Husinec Řež Czech Republic

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Flemingovo nám 2 166 10 Praha 6 Czech Republic

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