Mn 2+ substitution within the {V 14 As 8 } polyoxovanadate archetype results in {Mn 2 V 12 As 8 } shells with trans ‐positioned heterometal positions

Solvothermal exploration of the As, V, Mn reaction system in the presence of aqueous diethylenetriamine (=dien) solution led to the discovery of [Mn II 4 V IV 12 As III 8 O 40 (dien) 4 (H 2 O)] ⋅ 3.5H 2 O, containing the first arsenato‐polyoxovanadate featuring a {Mn 2 V 12 As 8 O 40 } cluster shell. In comparison to its parental {V 14 As 8 O 42 } archetype, two vanadyl (VO 2+ ) units at opposite ends of the polyoxovanadate shell here are substituted by Mn 2+ centers. In the solid state, these {Mn 2 V 12 As 8 O 40 } units are joined into rods by sharing common Mn−O−V linkages. Expansion of the cluster shell by two further Mn 2+ sites via Mn−O=V bridges generates a {Mn 4 V 12 As 8 O 40 } moiety. Three Mn 2+ cations are joined by monodentate‐coordinating dien ligands, which link the rods into layers. The dien ligands here coexist in three different coordination modes: monodentate, bidentate and tridentate, which is rarely observed. Magnetic susceptibility measurements show the expected significant antiferromagnetic coupling interactions between all spin centers present in the title compound, namely the isotropic spin‐5/2 Mn 2+ centers and the isotropic spin‐1/2 vanadyl groups, in line with most other heterometal‐substituted arsenato‐polyoxovanadate(IV) clusters.