Hydrothermal Synthesis of a Novel Se12 Ring in [{(NH4)2[Mo3S11.72Se1.28]}2[Se12]]

A new form of selenium, neutral cyclo-Se12 (see picture), is entrapped within ionic layers of the title compound. It arises from the hydrothermal reaction between (NH4)2MoS4 and Na2S3Se3. The D3d-symmetric twelve-membered ring is embedded in a trigonal lattice of [Mo3(S11.72Se1.28)]2− clusters and ammonium cations. The title compound forms black, hexagonal platelets.