Trinuclear molybdenum cluster sulfides coordinated to dithiolene ligands and their use in the development of molecular conductors

The present article reviews synthetic approaches to efficiently prepare Mo3S7 clusters coordinated to 1,2-bis-dithiolene ligands of general formula [Mo3S7(dithiolene)3]2− where dithiolene stands for tfd (bis(trifluoromethyl)-1,2-dithiolene), bdt (1,2-benzenedithiolene), mnt (maleonitriledithiolene), tdas (1,2,5-thiadiazole-3,4-dithiolene), dmid (1,3-dithia-2-one-4,5-dithiolene), dmit (1,3-dithia-2-thione-4,5-dithiolene) and the diselenolene dsit (1,3-dithia-2-thione-4,5-diselenolene). These [Mo3S7(dithiolene)3]2− dianions serve as starting materials to access new dithiolene clusters featuring Mo3S4 and Mo2O2S2 cluster cores. The electrochemical and spectroscopic properties as well as solid state structures of Mo3S7/dithiolene compounds are also described. These C3-symmetry [Mo3S7(dithiolene)3]2− molecules inherently possess degenerate frontier orbitals and display a rich structural diversity due to the electrophilic character of the three sulfur atoms in axial positions. These characteristics make the [Mo3S7(dithiolene)3]2− dianions, versatile targets for the development of new molecular conductors. Several examples of hybrid charge-transfer salts based on TTF-donors and [Mo3S7(dithiolene)3]2−/[Mo3S7X6]2− dianions (X = Cl, Br) are discussed as well as the preparation of the first family of cluster-based single-component magnetic conductors of formula Mo3S7(dithiolene)3.