THE METASTABLE PARTIALLY POSITIVELY CHARGED Se₆ MOLECULE: PREPARATION, CHARACTERISATION AND X-RAY CRYSTAL STRUCTURE OF [Ag₂(Se₆)(SO₂)₂][Sb(OTeF₅)₆]₂, [Ag₂Se₆][AsF₆]₂ AND [AgSe₆][Ag₂(SbF₆)₃]

Abstract

Reactions designed to give Se₆[Sb(OTeF₅)₆]₂ by the reaction of Se₂Br₂, 4Se, and 2Ag[Sb(OTeF₅)₆] lead to products that include [Ag₂(Se₆)(SO₂)₂][Sb(OTeF₅)₆]₂(1). The distorted cubic (Ag₂Se₆ ²⁺) _n consists of a Se₆ molecule bicapped by two silver cations (local D_3d sym.). Reactions of AgMX₆ (M = As, Sb) with selenium in liquid SO₂ yielded crystals of [Ag₂Se₆][AsF₆]₂ (2) and [AgSe₆][Ag₂(SbF₆)₃] (3). Both salts contain stacked arrays of [AgSe₆]⁺ half-sandwich cationic units. [Ag₂Se₆][AsF₆]₂ in addition contains stronger, linear Se─Ag─Se horizontal linkages between the vertically stacked cationic columns. [AgSe₆][Ag₂(SbF₆)₃] features a remarkable three-dimensional [Ag₂(SbF₆)₃]⁻ anion held together by strong Sb─F···Ag contacts between component Ag⁺ and SbF₆ ⁻ ions. Hexagonal channels through this honeycomb-like anion are filled by the stacked [AgSe₆ ⁺]_x.

Keywords:

• Disilverhexaseleniumbis(sulfurdioxide)(2+)
• disilverhexaselenium(2+)
• hexafluoroarsenate
• hexafluoroantimonate
• hexakis (pentafluorooxotellurato)-antimonate
• hexaselenium
• polymeric silverhexaselenium(1+)
• silver(1+)
• x-ray

This work was supported by the Natural Science and Engineering Research Council of Canada NSERC (J.P.). Dr. Ingo Krossing is grateful to the Alexander von Humboldt Foundation in Bonn, Germany, for providing a Feodor-Lynen Fellowship. Dr. Folker Steden thanks DAAD for providing a doctoral fellowship (Hochschulprogramms III von Bund und Ländern).