A Bimetallic Benzene-1,2,4,5-Tetrathiolate (btt) Molybdenocene Complex Cp 2 Mo(btt)MoCp 2 : Radical and Diradical States

Benzene-1,2,4,5-tetrathiolate (btt) has been used as a bridging ligand to prepare a redox active (molybdenocene dithiolene)-based bimetallic complex Cp Mo(btt)MoCp , 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 MoS C metallacycles are electronically coupled in the monocationic as in the dicationic state. Two salts of the dication [Cp Mo(btt)MoCp ] have been structurally characterized with PF and HSO counterions, showing different chair or boat conformations associated with variable folding angles of the two MoS C 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.