A bimetallic benzene-1,2,4,5-tetrathiolate (btt) molybdenocene complex Cp2Mo(btt)MoCp2: radical and diradical states

International audience; Benzene-1,2,4,5-tetrathiolate (btt) has been used as a bridging ligand to prepare a redox active (molybdenocene dithiolene)-based bimetallic complex Cp2Mo(btt)MoCp2, which exhibits four successive electron transfers up to the tetracation. Spectro-electrochemical investigations together with DFT and TD-DFT calculations evidence that the two electroactive MoS2C2 metallacycles are electronically coupled in the monocationic as in the dicationic state. Two salts of the dication [Cp2Mo(btt)MoCp2]2+ have been structurally characterized with PF6- and HSO4- counterions, showing different chair or boat conformations associated with variable folding angles of the two MoS2C2 metallacycles along the S---S hinge. The bis-oxidized dicationic complex exhibits a diradical character, with both radicals essentially localized on the metallacycles and with antiferromagnetic coupling evidenced from magnetic susceptibility measurements.