The first selenoiridate anion [Ir(Se-4)(3)](3-) has been obtained as a [K(18-crown-6)](+) salt through the reaction of [Ir(CH3CN)(2)(COE)(2)][BF4] with [K(18-crown-6)](2)[Se-4] in acetonitrile/DMF at -50 degrees C. [Ir(Se-4)(3)](3-) represents only the second example of a group 9 chalcogenometalate. Variable-temperature Se-77 NMR data provide evidence of an equilibrium between two conformers of [Ir(Se-4)(3)](3-) in solution with Delta H = 2.5(5) kcal mol(-1) and Delta S = 11.5(2.2) cal mol(-1) K-1. In the solid state the anion is a Lambda delta delta delta/Delta lambda lambda lambda racemate.