Synthesis and Structure of the Novel Pentaselenidohexaarsenate(I,II) Cluster Anion [As6Se5]2−

Methanolothermal reaction of MnCl₃(9‐ane‐N₃)] with As₂Se₃ at 150 °C in the presence of Cs₂CO₃ affords violet‐coloured Mn(9‐ane‐N₃)₂]As₆Se₅ ( 1 ). Its novel tricyclic selenidoarsenate(I,II) anion As₆Se₅]^2? contains two five‐membered As₃As(Se)Se] rings that are symmetry‐related by a crystallographic C₂ axis passing through the common As^I‐As^I bond between their respective first two ring members. The adjacent As^I atoms in the individual rings are bridged by the Se atom of the third As₄Se] ring.