Cs 3 Se 22 , a Selenium‐rich Caesium Polyselenide containing Se 8 Crowns and $^{3}_{\infty}\rm [Se_{6}^{3-}]$ Anions with Radical Character

Cs 3 Se 22 can be prepared together with the known compounds Cs 2 Sn 2 Se 6 and Cs 4 Sn 2 Se 6 by reacting Cs 2 CO 3 and Sn in a CH 3 OH/en solution at 120 °C. The presence of CuCl and the macrocyclic ligand 1,10‐dithia‐18‐crown‐6 are essential for product formation. The caesium polyselenide consists of anionic nets $^{3}_{\infty}\rm [Se_{6}^{3-}]$ that are separated by two layers of discrete Se 8 rings. Within the polymeric anions pairs of Se 3 ·− radical anions and Se 3 2− anions are linked through secondary interactions.