Mechanistic insight from activation parameters for the reaction of a ruthenium hydride complex with CO2 in conventional solvents and an ionic liquid.
Detailed kinetic studies were performed on the reaction of [Ru(II)(terpy)(bpy)H](+) (terpy = 2,2',6',2″-terpyridine; bpy = 2,2'-bipyridine) with CO(2) in conventional solvents (water, methanol, and ethanol) and in the ionic liquid [emim][NTf(2)] ([emim] = 1-ethyl-3-methyl-imidazolium; [NTf(2)] = bistrifluoromethylsulfonylamide). Second-order rate constants and activation parameters (ΔH(‡), ΔS(‡), and ΔV(‡)) were determined for the reaction in all solvents. The second-order rate constants correlate with the acceptor number of the solvent, whereas the activation parameters support the associative nature of the reaction. The results in water, especially the activation entropy (+14 ± 2 J K(-1) mol(-1)) and activation volume (-5.9 ± 0.6 cm(3) mol(-1)), differ significantly from those found for the other solvents.
Inorganic Chemistry, Department of Chemistry and Pharmacy, University Erlangen-Nuremberg, Egerlandstr. 1, 91058 Erlangen, Germany.
Simon
S
Kern
Rudi
R
van Eldik
D015082:2,2'-Dipyridyl / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D015394:Molecular Structure; D011725:Pyridines / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry; D012997:Solvents / Q000737:chemistry
C517923:(2,2'-6',2'')-terpyridine; D056831:Coordination Complexes; D052578:Ionic Liquids; D011725:Pyridines; D012997:Solvents; D002245:Carbon Dioxide; D015082:2,2'-Dipyridyl; D012428:Ruthenium; D006859:Hydrogen