Ruthenium(III) bromide can be prepared by the reaction of ruthenium metal with bromine at high temperature and pressure (720 K and 20 bar):[3]
2 Ru + 3 Br2 → 2 RuBr3
Structure
The crystal structures of ruthenium(III) bromide contain parallel (RuBr3)∞ columns. The compound undergoes a phase transition around 384 K (111 °C) from an ordered orthorhombic structure in space groupPnmm with alternating long and short Ru-Ru distances to a disordered hexagonal TiI3-like structure in space group P63/mcm with (on average) equal Ru-Ru distances.[1] In the disordered polymorph, the Ru-Ru distances are not believed to actually be equal but appear so due to a random distribution of two distinct column conformations. Both polymorphs consist of hexagonally close-packed bromide ions.[4]
References
^ abHillebrecht, H.; Ludwig, T.; Thiele, G. (2004). "About Trihalides with TiI3 Chain Structure: Proof of Pair Forming of Cations in β-RuCl3 and RuBr3 by Temperature Dependent Single Crystal X-ray Analyses". Zeitschrift für Anorganische und Allgemeine Chemie. 630 (13–14): 2199–2204. doi:10.1002/zaac.200400106.