NMR approach for the identification of dinuclear and mononuclear complexes: The first detection of [Pd(SPh)2(PPh3)2] and [Pd2(SPh)4(PPh3)2] – The intermediate complexes in the catalytic carbon–sulfur bond formation reaction

In the present study we have analyzed the nature of palladium complexes in the catalytic system for selective carbon–sulfur bond formation via the addition of S–S and S–H bonds to alkynes. For the first time the mononuclear and dinuclear palladium complexes were clearly detected by DOSY NMR under the catalytic conditions. It was demonstrated that the concentration of these palladium complexes strongly depends on the amount of phosphine ligand available under reaction conditions.

Graphical abstractDetection of mononuclear and dinuclear palladium complexes was carried out by DOSY NMR under catalytic conditions. The concentration of these palladium complexes was found strongly dependent on the amount of phosphine ligand available in the system. It was evidenced that both types of complexes can contribute to the product formation.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights►Mononuclear and dinuclear transition metal complexes detection by DOSY NMR. ►The nature of the catalytic system by in situ NMR monitoring. ►Catalytic activity of mononuclear and dinuclear transition metal complexes.