Towards 'S4' Molybdenum with Two Labile Sites: New Ligands for Molybdenum Bisdithiolenes

Molybdenum disulfide (MoS2) catalysts are used for hydrodesulfurization processes, needed for the removal of sulfur from oil feedstocks. The commonly accepted active site of MoS2 is believed to have a S4 pyramidal geometry with molybdenum (IV) at the apex. This work is interested in small molecules as models. Recent work has shown that one ligand can be removed from a molybdenum trisdithiolene by reacting the metal complex with an olefin creates a labile chelate cap. The resulting structure resembles the active site of interest. The present contribution will show approaches to molybdenum bisdithiolenes with one or two labile solvent molecules. The use of acetonitrile, adiponitrile, isobutyronitrile, and oxalate has been investigated. A complex containing two different labile moieties (tetrahydrothiophene, acetonitrile) was crystallographically characterized. Other nitrile molybdenum complexes were monitored using NMR spectroscopy. Two complexes have been characterized with an oxalato ligand; a single unit, and a dimer.MAS