Ruthenium(III) iodide

Ruthenium(III) iodide is a chemical compound containing ruthenium and iodine with the formula RuI3. It is a black solid.

Preparation
Ruthenium(III) iodide can be prepared in several ways.

The reaction of ruthenium tetroxide with aqueous hydroiodic acid:


 * RuO4 + excess HI -> RuI3

The thermal decomposition of pentaammineruthenium(III) iodide:


 * Ru(NH3)5I3 -> RuI3 + 5 NH3

The salt metathesis reaction of hydrated ruthenium(III) chloride with potassium iodide in aqueous solution:


 * RuCl3*xH2O + 3 KI -> RuI3 + 3 KCl + xH2O

Direct combination of the elements has been reported to succeed under some conditions (350 °C) but not others (500 °C and 20 atm):


 * 2 Ru + 3 I2 → 2 RuI3

Structure
Ruthenium(III) iodide adopts an extended structure with octahedral coordination geometry at ruthenium. There is some doubt about the characterisation of ruthenium(III) iodide and it may be an oxohalide or a hydroxyhalide.