Reactions of [Ru(NO)Cl5]2− with pseudotrilacunary {XW9O33}9− (X = AsIII, SbIII) anions

Abstract

Reactions of [Ru(NO)Cl₅]²⁻ with pseudotrivacant B-α-[XW₉O₃₃]⁹⁻ (X = As^III, Sb^III) at 160 °C result in the rearrangement of polyoxometalate backbones into {XM₁₈} structures. In the case of arsenic, oxidation of As^III to As^V takes place with the formation of a mixture of plenary and monosubstituted Dawson [As₂W₁₈O₆₂]⁶⁻ and [As₂W₁₇Ru(NO)O₆₁]⁷⁻ anions, of which the latter was isolated as Me₂NH₂⁺ (DMA-1a and DMA-1b) and Bu₄N⁺ (Bu₄N-1) salts and fully characterized. Both α₁ and α₂ isomers of [As₂W₁₇Ru(NO)O₆₁]⁷⁻ were present in the reaction mixture; pure [α₂-As₂W₁₇Ru(NO)O₆₁]⁷⁻ was isolated as the Bu₄N⁺ salt. In the case of antimony, [SbW₉O₃₃]⁹⁻ is converted into a mixture of [SbW₁₈O₆₀]⁹⁻ and [SbW₁₇{Ru(NO)}O₅₉]¹⁰⁻. The formation of trisubstituted [SbW₁₅{Ru(NO)}₃O₅₇]¹²⁻ as a minor byproduct was detected by HPLC-ICP-AES. The monosubstituted [SbW₁₇{Ru(NO)}O₅₉]¹⁰⁻ anion was isolated as DMAH⁺ (DMA-2) and mixed inorganic cation (CsKNa-2) salts and characterized by XRD, HPLC-ICP-AES, EA and TGA techniques. X-ray analysis shows the presence of the {Ru(NO)}-group in the 6-membered (“equatorial”) belt of the Sb-free hemisphere. The experimental findings were confirmed and interpreted by means of quantum chemical calculations.