Two new 3-D boratopolyoxovanadate architectures based on the [V12B16O50(OH)8]12− cluster with different metal linkers

Abstract

Two new 3-D boratopolyoxovanadates {[Zn₂NaV₁₂B₁₆O₅₀(OH)₈(H₂O)₇]}·7(H₃O)·4H₂O (1) and [Cd₃Na_3.5V₁₂B₁₆O₅₀(OH)₈(H₂O)₈]·2.5(H₃O)·11H₂O (2) were synthesized employing hydrothermal reactions and structurally characterized. Both 1 and 2 contain the boratopolyoxovanadate cluster [V₁₂B₁₆O₅₀(OH)₈]¹²⁻ built up from one continuous contorted [V₁₂O₃₆] ring and two [B₈O₁₇(OH)₄] clusters. The clusters [V₁₂B₁₆O₅₀(OH)₈]¹²⁻ in both 1 and 2 are linked by Zn²⁺/Cd²⁺ ions into the sql layer and self-penetrating sql layer, respectively, which are further connected by Na⁺ ions to form the 3-D boratopolyoxovanadate architectures. The most interesting feature is that each [V₁₂B₁₆O₅₀(OH)₈]¹²⁻ unit in 2 acts as a multidentate ligand coordinated with six Cd²⁺ ions and eight Na⁺ ions, which represents the highest coordination number of [V₁₂B₁₆O₅₀(OH)₈]¹²⁻ with metal cations to date. Magnetic measurements illustrate that both 1 and 2 have antiferromagnetic exchange interactions between metal centers.