Microscopic studies of transition metal chalcogenides

The reaction of single crystals of transition metal dichalcogenides (MX2 layer structures) with n-butyllithium to form LiMX2 have been followed with the optical microscope. Small crystals are observed to intercalate Li with movement of a distinct front through the crystal. Larger crystals crack but remain intact. The reaction of single crystals of transition metal trichalcogenides (MX3-chain structures) to form Li3MX3 have also been observed and here large crystals fragment to smaller crystals. Both reactions are topochemical reactions in which structural integrity is retained. In the first case (MX2) slight structural rearrangement occurs and in the second case moderate structural rearrangement occurs. The reaction of TiS2 with NH3 is also discussed.