Preparation of a series of chalcogenolate-bridged diruthenium complexes and their catalytic activities toward propargylic substitution reactions

A series of chalcogenolate(Se,Te)-bridged diruthenium complexes (neutral and cationic) as well as their allenylidene complexes have been newly prepared, and their catalytic activities toward the propargylic substitution reactions have been compared with those using the corresponding thiolate(S)-bridged complexes. Results of both catalytic and stoichiometric reactions using these complexes together with their redox properties show that the ease of the charge transfer from one Ru. atom (working as an electron pool) to the other in the complexes (synergistic effect) may be one of the important factors in promoting a key ligand exchange step for these catalytic reactions. The finding presented here may provide a new possibility of polynuclear transition metal complexes for organic transformations.