LAUSR

A detailed kinetic study of the reduction of trans-[RuCl2(dipicOEt)2]-, where dipicOEt = dipicolinate mono ethyl ester anion, by L-ascorbic acid that leads to the formation of the corresponding Ru(II) complex, was carried out spectrophotometrically using the stopped-flow technique. The reaction was studied as a function of [AscH2]T and pH. The observed kinetic traces could only be fitted by a three-exponential function, characteristic for three parallel reaction paths. The complex was isolated as {[Na(H2O)2][trans-RuCl2(dipicOEt)2]}n of which a single crystal X-ray structure was determined. Detailed spectroscopic studies on the complex present in aqueous solution showed that under the selected experimental conditions only a single complex species is present in solution. The observed complication is suggested to arise from the low driving force of the reaction during which the re-oxidation of Ru(II) by the semi-oxidized L-ascorbic acid, i.e. ascorbyl radical Asc*-, accounts for the apparent three exponential behavior of the reaction. The results are in excellent agreement with those of a recent study on the same reaction for cis-dichloridobispicolinatoruthenate(III) (Eur. J. Inorg. Chem., 2016, 5380-5386).