While Tl+ is stabilised by the inert-pair effect, this inert pair of 6s electrons is still able to participate chemically, so that these electrons are stereochemically active in aqueous solution.
wˌaɪl tˌiːˈɛl plˈʌs ɪz stˈeɪbəlˌaɪzd baɪ ðɪ ɪnˈɜːtpˈɛɹ ɪfˈɛkt, ðɪs ɪnˈɜːt pˈɛɹ ʌv sˈɪks ᵻz ᵻlˈɛktɹɑːnz ɪz stˈɪl ˈeɪbəl tə pɑːɹtˈɪsᵻpˌeɪt kˈɛmɪkli, sˌoʊ ðæt ðiːz ᵻlˈɛktɹɑːnz ɑːɹ stˌɛɹɪoʊkˈɛmɪkli ˈæktɪv ɪn ˈeɪkwɪəs səlˈuːʃən.