title: Mechanistic studies on fast ligand substitution reactions of Pt(II) in different ionic liquids: role of solvent polarity and ion-pair formation.
abstract: The effect of several imidazolium-based ionic liquids on the mechanism of a classical ligand substitution reaction of [Pt(terpyridine)Cl] (+) with thiourea was investigated. A detailed kinetic study as a function of the nucleophile concentration and temperature was undertaken under pseudo-first-order conditions using stopped-flow techniques. Polarity measurements were performed for the employed ionic liquids on the basis of solvatochromic effects, and they show similarities with conventional polar solvents. Density-functional theory calculations (RB3LYP/LANL2DZp) were employed to predict the ion-pair stabilization energy between the ionic components of the ionic liquids and/or between the anions of the ionic liquids and the cationic Pt (II) complex. These data illustrate how the anions of the ionic liquids can affect the investigated substitution reaction. In general, the substitution mechanism in ionic liquids was found to have an associative character similar to that in conventional solvents. The observed deviations reflect the influence of the ionic liquid on the interaction between the anionic component of the liquid and the positively charged complex.
authors.affiliation: Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nurnberg, Egerlandstr. 1, 91058 Erlangen, Germany.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Begel
authors.forename: Peter
authors.initials: P
authors.lastname: Illner
authors.forename: Simon
authors.initials: S
authors.lastname: Kern
authors.forename: Ralph
authors.initials: R
authors.lastname: Puchta
authors.forename: Rudi
authors.initials: R
authors.lastname: van Eldik
mesh_terms: D052578:Ionic Liquids / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D009942:Organometallic Compounds / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D011312:Pressure; D011725:Pyridines / Q000737:chemistry; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: C517923:(2,2'-6',2'')-terpyridine; D052578:Ionic Liquids; D008024:Ligands; D009942:Organometallic Compounds; D011725:Pyridines; D012997:Solvents; D010984:Platinum