Kinetics and Mechanism of the Reaction of a Ruthenium(VI) Nitrido Complex with HSO3- and SO32- in Aqueous Solution

The kinetics and mechanism of the reaction of S-IV (SO32- + HSO3-) with a ruthenium(VI) nitrido complex, [(L)Ru-VI(N)(OH2)](+) ((RuN)-N-VI, L = N,N'-bis(salicylidene)-o-cyclohexyldiamine dianion), in aqueous acidic solutions are reported. The kinetic results are consistent with parallel pathways involving oxidation of HSO3- and SO32- by (RuN)-N-VI. A deuterium isotope effect of 4.7 is observed in the HSO3- pathway. Based on experimental results and DFT calculations the proposed mechanism involves concerted N S bond formation (partial N-atom transfer) between RuVIN and HSO3- and H+ transfer from HSO3- to a H2O molecule.