Synthesis, Structures, and Properties of New Chalcogenide‐Capped Octahedral Hexatechnetium(III) Complexes [Tc 6 S 8 X 6 ] 4– (X = Br, I), [Tc 6 Se 8 I 2 ], and [Tc 6 Te 15 ]

Chalcogenide‐capped octahedral hexatechnetium(III) complexes, Cs 4 [Tc 6 S 8 Br 6 ] · CsBr (Cs 4 [ 1 ] · CsBr) and (PPh 4 ) 4 [Tc 6 S 8 Br 6 ] {(PPh 4 ) 4 [ 1 ]}, (PPh 4 ) 4 [Tc 6 S 8 I 6 ] {(PPh 4 ) 4 [ 2 ]}, [Tc 6 Se 8 I 2 ] ([ 3 ]), and [Tc 6 Te 15 ] ([ 4 ]) were synthesized. Single‐crystal X‐ray structural studies were carried out for Cs 4 [ 1 ] · CsBr, [ 3 ], and [ 4 ]. Sulfide‐capped octahedral hexatechnetium(III) clusters [ 1 ] 4– and [ 2 ] 4– are discrete complex anions, whereas the selenide‐ and telluride‐capped hexatechnetium(III) complexes adopt extended polymeric structures. A cyclic voltammogram of [ 1 ] 4– in CH 3 CN showed two one‐electron redox waves: Tc 6 (24e/23e) and Tc 6 (23e/22e). The potential of the Tc 6 (24e/23e) process is more positive than that of the Re 6 (24e/23e) process for the hexarhenium analog [Re 6 S 8 X 6 ] 4– (X = Br, I), whereas that of the Tc 6 (23e/22e) process shifts to negative values compared to the potential of the Re 6 (23e/22e) process. Thus, the Tc 6 (23e) mixed‐valence state is thermodynamically less stable than Re 6 (23e).