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A new arsenato-polyoxovanadate with the composition {[Ni(dien)2]3[V6As8O26]}2+·2 Cl– has been crystallized under solvothermal conditions as turquoise block-like crystals. The central structural feature is the [V6IVAs8IIIO26]4– cluster anion, which is composed of two trinuclear {V3O11} groups consisting of three edge-sharing VO5 polyhedra. Pairs of pyramidal AsO3 moieties share a common corner forming As2O5 units, which interconnect the {V3O11} groups. One of the [Ni(dien)2]2+ complexes adopts the s-fac (Ni1) and the second complex the mer configuration (Ni2). The Cl− anion is involved in strong hydrogen bonding interactions and links the [Ni(dien)2]2+ complexes to form twelve-membered rings which host the [V6As8O26]4– cluster anions. The Hirshfeld surface analysis yields a detailed picture of the intermolecular interactions revealing clear differences for the two unique [Ni(dien)2]2+ complexes. Intermolecular contacts also include As⋯H, O⋯H and H⋯H interactions. In the electronic spectrum the bands of d–d transitions of the vanadyl group and of the Ni2+ cations overlap, preventing a detailed analysis. [ABSTRACT FROM AUTHOR]

Three new arsenato-polyoxovanadates with the composition [M(en)3]2[V6As8O26] (M = Co2+ (I), Zn2+ (II), and Cd2+ (III)) were synthesized under solvothermal conditions in high yields, thus significantly enhancing the knowledge of As-rich polyoxovanadate cluster chemistry. The compounds are isostructural and feature the very rare [V6IVAs8IIIO26]4− cluster anion. The cluster shell is constructed by interconnection of two trimeric {V3O11} groups consisting of three edge-sharing VO5 polyhedra and four As2O5 units, which are formed by two corner-sharing AsO3 pyramids. While the As2O5 group is a common structural feature in arsenato-polyoxovanadates, the {V3O11} unit is only observed in V-rich high-nuclear heteroatom-containing polyoxovanadates {V14E8} (E = As, Sb, Ge). The complexes adopt the Λ (δδδ) conformation, which is the most stable arrangement. Interestingly, the unit cell parameters do not scale with the volume of the [M(en)3]2+ complexes, assuming a constant volume of the anion. Only a very detailed Hirshfeld surface analysis revealed that the van der Waals volume of the {V6As8O26} moiety is the smallest for the Cd-containing compound, while the volumes of the anions in the other two compounds are very similar. Therefore, the observed trends of the lattice parameters can be explained on the basis of these findings. Furthermore, intermolecular interactions include As⋯H contacts in addition to O⋯H and H⋯H interactions. The electronic spectrum of I contains d–d transitions of the vanadyl group and of the Co2+ cation. As expected only the d–d transitions of the VO2+ unit occur for II and III. [ABSTRACT FROM AUTHOR]

Solvothermal exploration of the As, V, Mn reaction system in the presence of aqueous diethylenetriamine (=dien) solution led to the discovery of [MnII4VIV12AsIII8O40(dien)4(H2O)] ⋅ 3.5H2O, containing the first arsenato‐polyoxovanadate featuring a {Mn2V12As8O40} cluster shell. In comparison to its parental {V14As8O42} archetype, two vanadyl (VO2+) units at opposite ends of the polyoxovanadate shell here are substituted by Mn2+ centers. In the solid state, these {Mn2V12As8O40} units are joined into rods by sharing common Mn−O−V linkages. Expansion of the cluster shell by two further Mn2+ sites via Mn−O=V bridges generates a {Mn4V12As8O40} moiety. Three Mn2+ 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 Mn2+ centers and the isotropic spin‐1/2 vanadyl groups, in line with most other heterometal‐substituted arsenato‐polyoxovanadate(IV) clusters. [ABSTRACT FROM AUTHOR]

The new coordination polymer Cr(en)2As2VO7 (en=ethylenediamine) was synthesized under solvothermal conditions as deep red crystals. In the crystal structure VO4 tetrahedra and As2O5 handles formed by corner-sharing of two AsO3 pyramidal units are joined by common oxygen atoms into an undulated chain that is directed along the crystallographic b-axis. The chain is decorated by [Cr(en)2]3+ complexes with the Cr3+ cation having bonds to two terminal O2- anions of the As²O5 moiety thus generating a CrN4O2 octahedron, which displays a cis-configuration. The connection mode between Cr3+ and As2O5 leads to formation of a six-membered CrAs2O3 ring. The chains are arranged in a layer-like fashion in the (001) plane and these layers are stacked along [001]. A large number of N-H···O and C-H···O hydrogen bonds generate a three dimensional network. A Hirshfeld surface analysis was performed for visualizing the extended interchain interactions. The hydrogen bonding interactions are clearly detected in the IR spectrum. The UV-Vis spectrum shows an absorption at 2.3 eV which is in agreement with the red color of the sample. [ABSTRACT FROM AUTHOR]

The new compound {[Mn(teta)]4V16Sb4O42} n ·[(H2O)12] n ( 1) was synthesized under solvothermal conditions. The crystal structure features the high nuclearity [V16IVSb4IIIO42(H2O)]8- cluster anion, which consists of two rings composed of 8 edge-sharing VO5 polyhedra. The rings are perpendicular to each other generating four niches, which are occupied by two VO5 pyramids and two handle-like Sb2O5 units. The two unique anions are each surrounded by eight Mn2+ centered complexes via Mn-Oterm-V bonds. Such an expansion has never been observed in heterometal polyoxovanadate chemistry. The connection mode between cluster anions and complex cations generates two individual layers stacked onto each other. Between the layers weak Sb ···O contacts are observed. The crystal water molecules are mainly located in the empty space between the layers. Upon heating H2O molecules are removed, while the crystal structure remains intact. The magnetic behavior is dominated by strong antiferromagnetic exchange interactions between the central V4+ ions, while the interaction between the cluster anion and central Mn2+ ions is significantly less pronounced. [ABSTRACT FROM AUTHOR]

The new compound {[Mn(teta)]4V16Sb4O42} n ·[(H2O)12] n ( 1) was synthesized under solvothermal conditions. The crystal structure features the high nuclearity [V16IVSb4IIIO42(H2O)]8- cluster anion, which consists of two rings composed of 8 edge-sharing VO5 polyhedra. The rings are perpendicular to each other generating four niches, which are occupied by two VO5 pyramids and two handle-like Sb2O5 units. The two unique anions are each surrounded by eight Mn2+ centered complexes via Mn-Oterm-V bonds. Such an expansion has never been observed in heterometal polyoxovanadate chemistry. The connection mode between cluster anions and complex cations generates two individual layers stacked onto each other. Between the layers weak Sb ···O contacts are observed. The crystal water molecules are mainly located in the empty space between the layers. Upon heating H2O molecules are removed, while the crystal structure remains intact. The magnetic behavior is dominated by strong antiferromagnetic exchange interactions between the central V4+ ions, while the interaction between the cluster anion and central Mn2+ ions is significantly less pronounced. [ABSTRACT FROM AUTHOR]

The new tungstovanadate (trenH)2(trenH2)2[W4V13O44]· ca.11H2O was prepared under solvothermal conditions in a basic solution at pH ≈ 12. The cluster core contains VIV/VV centers with delocalized spins exhibiting strong antiferromagnetic exchange interactions as evidenced by temperature-dependent magnetic susceptibility measurements pointing to an S = 1/2 magnetic ground state. The structure features an eight-membered ring composed of four alternating edge-sharing VO5 pyramids and VO6 octahedra encapsulating a central Keggin fragment. [ABSTRACT FROM AUTHOR]