Synthesis and characterization of homoleptic ruthenium(II) imidazole complexes, and a carbonyl species derived by CO abstraction from DMF

Abstract

[Ru(II)(L)6]2+ complexes were synthesized from [Ru(DMF)6][CF3SO3]3; DMF = dimethylformamide, L = imidazole (Im), N-methylimidazole (NMeIm) and 5-methylimidazole (5MeIm). The 2-methylimidazole complex trans-[Ru(CO)(DMF)(2MeIm)4][CF3SO3]2 (4) was also synthesized via a reaction involving abstraction of CO from DMF; 4 loses CO reversibly at ambient temperature to form [Ru(DMF)(2MeIm)4][CF3SO3]2 (5), and the DMF can be removed to generate a [Ru(CF3SO3)x(2MeIm)4][CF3SO3]y species (x = 2, y = 0, or x = 1 = y), containing coordinated triflate. The complexes were characterized by elemental analysis, conductivity, UV-vis, NMR, and IR spectroscopies. The structures of [Ru(Im)6][CF3SO3]2 (1), [Ru(NMeIm)6][CF3SO3]2 (2), and [Ru(5MeIm)6][CF3SO3]2 (3) were established by X-ray crystallographic analyses. Crystals of 1, are triclinic, a = 7.4010(6), b = 9.9846(15), c = 11.275(2) Å, α = 113.469(5), β = 92.419(2), γ = 94.737(2)°, Z = 1, space group P1 ; those of 2, are trigonal, a = 11.558(2), c = 8.109(3) Å, Z = 1, space group P3; and those of 3, are trigonal, a = 12.6547(4), c = 20.4078(12) Å, Z = 3, space group R3. The structures were solved by Patterson methods and refined by full-matrix least-squares procedures to R(F) = 0.029, 0.034, and 0.034 (R w (F2) = 0.055, R w (F) = 0.031, and R w (F2) = 0.058), respectively. Key words: hexakis(imidazole)ruthenium(II) triflates, crystal structures, CO abstraction.