Reductive thiocyanolysis of tetraoxorhenate (VII): Synthesis, crystal structure, catalytic oxidation and kinetic studies of (PPh4)2[Re(NCS)6] and (PPh4)2[ReO(NCS)5]

Thiocyanate ions reduce perrhenate (ReO4-) in aqueous acidic solution, and on addition of a suitable countercation (PPh4Cl) afford (PPh4)2[Re(NCS)6] (1) and (PPh4)2[ReO(NCS)5] (2), which have been confirmed by X-ray crystallography. The kinetics of the above reaction has been studied. Both the complexes exhibit efficient and highly selective catalytic epoxidation ability in the presence of NaHCO3 as a co-catalyst and competent catalytic properties in the selective oxidation of alcohols to the corresponding aldehydes or ketones in the presence of pyrazole as an additive and sulfides to sulfoxides and sulfones. H2O2 was used as the terminal oxidant in all the above-mentioned oxidation reactions.

Graphical abstractTwo rhenium thiocyanate complexes 1 and 2 were synthesized via reductive thiocyanolysis and their crystal structure was determined. Both were found to be efficient catalysts in the oxidation of olefins, alcohols and sulfides. The kinetics of the thiocyanolysis reaction was also studied.Figure optionsDownload full-size imageDownload as PowerPoint slide