Hydrogenation of 1-hexene by a triruthenium cluster stabilized with a face-capping 1,3-dithiacyclohexane ligand

Abstract

Homogeneous hydrogenation of 1-hexene to hexane was studied using a triruthenium cluster containing a face-capping ligand, HRu 3(CO) 9( μ 3- η 3-1,3-dithiacyclohexane) ( 1), as a catalyst precursor. The catalytic activity of 1 was studied as a function of temperature (98–140°C), H 2 pressure (10–60 bar) and catalyst concentration. The highest hydrogenation rate of 0.085 mol/h was measured at 141°C and 60 bar of H 2 pressure. A linear dependence between the catalytic activity of 1 and the H 2 pressure was observed in the pressure range of 10–50 bar, but equalizing at higher pressures (> 50 bar). A rise in the temperature causes an increase in catalytic activity but at the same time enhances the fragmentation of 1 and the formation of a brown precipitate. The fragmentation product was not active in hydrogenation but shows moderate isomerization activity. A possible mechanism for the hydrogenation of 1-hexene by 1 is presented.