Mn²⁺ substitution within the {V₁₄As₈} polyoxovanadate archetype results in {Mn₂V₁₂As₈} shells with trans‐positioned heterometal positions

Abstract

Dedicated to Prof. Dr. Josef Breu on the Occasion of his 60th BirthdaySolvothermal 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 MnÀ OÀ V linkages. Expansion of the cluster shell by two further Mn 2 + sites via MnÀ 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.