Abstract <p>An efficient method was developed for the introduction of a dimethylammonium group into the pendant substituent at <i>nido</i>-carborane based on the alkylation of the trimethylammonium salt of 1-mercapto-<i>ortho</i>-carborane with α,ω-dihaloalkanes and subsequent reaction of the obtained ω-haloalkyl derivatives with dimethylamine. Thus, the reaction of (Me₃NH)[1-S-1,2-C₂B₁₀H₁₁] with an excess of 1,2-dibromoethane and 1,3-dibromopropane afforded the corresponding <i>ortho</i>-carborane derivatives 1-Br(CH₂)_<i>n</i>S-1,2-C₂B₁₀H₁₁ (<i>n</i> = 2, 3). Reactions of these derivatives with an excess of dimethylamine in tetrahydrofuran resulted in the exchange of the halogen atom for a dimethylamino group and were accompanied by deboronation of the <i>closo</i>-carborane cage to the anionic <i>nido</i>-form. As a result, two <i>C</i>-substituted <i>nido</i>-carborane derivatives with a pendant Me₂NH-group and varying spacer lengths between the carborane cage and the donor fragment, 7-Me₂HN(CH₂)_<i>n</i>S-7,8-C₂B₉H₁₁ (<i>n</i> = 2, 3), were synthesized. The obtained compounds are of interest as heterofunctional ligands of the η⁵κ¹-type.</p>