Methanolothermal Synthesis of [Mn(en) 3 ][Mn 2 (SbSe 4 ) 2 (en) 4 (H 2 O)] [Mn(en) 3 ][{Mn(en) 2 (H 2 O)} 2 (μ‐SbSe 4 )][Mn(μ‐SbSe 4 )(en) 2 ]Cl 2 representing the First Example of a Transition Metal‐containing Ternary Catena‐Selenidoantimonate(V)

[Mn(en) 3 ][Mn 2 (SbSe 4 ) 2 (en) 4 (H 2 O)] ( 1 ) and [Mn(en) 3 ][{Mn(en) 2 (H 2 O)} 2 (μ‐SbSe 4 )] [Mn(μ‐SbSe 4 )(en) 2 ]Cl 2 ( 2 ) may be prepared by methanolothermal reaction of Mn(OOCCH 3 ) 2 · 4H 2 O with elemental Sb and Se in the presence of CsCl in a 1:1 CH 3 OH/en mixture at 190°C. The [Mn 2 (SbSe 4 ) 2 (en) 4 (H 2 O)] 2− anions of 1 contain two [Mn(en) 2 ] 2+ fragments bridged by a single Se atom of an SbSe 4 4− anion in a 1κ Se : 2κ Se manner. The remaining sites in the Mn II octahedral coordination spheres are occupied by a κ Se coordinating [SbSe 4 ] 3− anion and a water ligand, respectively. In contrast, black coloured 2 contains both polymeric $^{1}_{\infty}$ [{Mn(μ‐SbSe 4 )(en) 2 } ‐ ] anions and disordered dinuclear [{Mn(en) 2 (H 2 O)} 2 (μ‐SbSe 4 )] + cations.