Isolation and Molecular Structure of Hexacyanoruthenate(III)

The [Ru(CN)₆]^3- ion is synthesized in aqueous solution and isolated as [Ph₄As]₃[Ru(CN)₆]·2H₂O (1). Compound 1 crystallizes as orange needles in the monoclinic space group P2₁/n with cell parameters a = 11.346(2) Å, b = 23.107(5) Å, c = 25.015(5) Å, β = 99.55(3)°, V = 6467.1(22) ų, Z = 4. The octahedral anion has Ru−C bond lengths in the range 2.023(6)−2.066(6) Å. DFT calculations reproduce experimental geometries for [M(CN)₆]^3- (M = Fe, Ru) equally well and yield significantly higher spin densities on the cyanide ligands in [M(CN)₆]^3- (M = Ru, Os) than in [Fe(CN)₆]^3-.