96826-82-3Relevant academic research and scientific papers
Kinetic studies on the photochemically activated solvation of [(η6-arene1)Ru(η6-arene 2)]2+ sandwich compounds
Karlen, Thomas,Hauser, Andreas,Ludi, Andreas
, p. 2213 - 2218 (2008/10/08)
Irradiation of the inert complexes [(η6-arene1)Ru(η6-arene 2)]2+ (arene = benzene, toluene, mesitylene, hexamethylbenzene, anisole, biphenyl, naphthalene, chrysene) in various solvents (H2O/H+, H2O/ H+/EtOH, acetonitrile, DMSO) leads to the fully solvated complexes [Ru(solvent)6]2+. The reaction occurs in two consecutive steps. The first step is the formation of the intermediate [(η6-arene)Ru(solvent)3]2+ with either arene1 or arene2 being replaced by solvent. The linear dependence of the observed rate constant for the first step on concentration of solvent as well as reactant is consistent with a second-order reaction. The formation of the half-sandwich intermediates depends on substituents on the arene, irradiation wavelength, temperature, and solvent. The magnitude of the quantum yields Φp is rationalized in terms of steric and electronic effects. The sequence for the release of arenes in the nonsymmetrically substituted complexes as monitored by 1H-NMR is shown to be consistent with a simple MO view, based on overlap strength in the electronic ground state of the starting compound. Luminescence properties of [(C6Me6)2Ru](tos)2 (tos = p-toluenesulfonate) are used for deriving information about the excited state.
Triaqua(benzene)ruthenium(II) and triaqua(benzene)osmium(II): Synthesis, molecular structure, and water-exchange kinetics
Stebler-R?thlisberger, Monika,Hummel, Wolfgang,Pittet, Pierre-A.,Bürgi, Hans-Beat,Ludi, Andreas,Merbach, André E.
, p. 1358 - 1363 (2008/10/08)
Solid salts of M(η-C6H6)(H2O)32+ (M = Ru, Os) are obtained by reacting [MCl2(η-C6H6)]2 with Ag+ in aqueous solution or by the reaction of Ru(H2O)62+ with cyclohexadiene in ethanol. [Ru(η-C6H6)(H2O)3]SO4 crystallizes in the orthorhombic space group Pbca with a = 12.892 (2) A?, b = 12.441 (1) A?, and c = 12.183 (2) A? (T = 125 K), and Z = 8. The structure was refined to 1.9% for 2168 reflections with Fo > 3σ(Fo). The relative arrangement of the benzene ring and the three water molecules is approximately staggered, the torsional angle being 19.2 (4)°. After correction for thermal motion, average distances are Ru-C = 2.164(4), C-C = 1.419 (5), and Ru-O = 2.117 (11) A?. The Ru-center of the benzene plane distance is 1.631 A?. Structural results obtained at 295 K agree with those at 125 K. Water-exchange rates at variable temperature and pressure were determined by line width measurements of 17O NMR spectra at 4.7 T. For Ru(η-C6H6)(H2O)32+ and Os(η-C6H6)(H2O)32+ the following results are obtained: k(298 K), 11.5 ± 3.1 and 11.8 ± 2.0 s-1; ΔH*, 75.9 ± 3.8 and 65.5 ± 2.2 kJ mol-1; ΔS*, +29.9 ± 10.6 and -4.8 ± 6.1 J K-1 mol-1; ΔV*, +1.5 ± 0.4 and +2.9 ± 0.6 cm3 mol-1. The reaction proceeds via an interchange mechanism (I) where the bond-breaking contribution has only a slightly larger weight than the bond-making one. The kinetic behavior indicates a strong trans-labilizing influence of the aromatic ligand.
