One-Dimensional Molybdenum Thiochlorides and Their Use in High Surface Area MoSx Chalcogels

New molybdenum thiochlorides, α-MoSCl3 and β-MoSCl3, have been synthesized by chemical vapor transport. A selenium analog, MoSeCl3, could also be prepared in the same way. The crystal structures consist of infinite chains stabilized by weak van der Waals forces. For the α-phase an infinite chain of ∞1[Mo2(S2)­Cl4Cl4/2] runs along the crystallographic c axis, while for the β-phase ∞1[Mo2(S2)­Cl3Cl6/2] chain passes through the b-axis. MoSeCl3 is isostructural to α-MoSCl3. The formal charge on molybdenum in these thiochlorides have been assigned by X-ray photoelectron spectroscopy (XPS) to be +IV. β-MoSCl3 and already known Mo3S7Cl4 and MoS2Cl3 are weakly paramagnetic. Thermal decomposition of molybdenum thiochlorides leads to MoS2. Red MoS2Cl3 and Mo3S7Cl4 exhibit band gaps of ∼2.07 and ∼2.11 eV, while black α-MoSCl3, β-MoSCl3, and MoSeCl3 exhibit band gaps of ∼1.2, 1.24, and 1.18 eV, respectively. The new thiochlorides can serve as precursors in the synthesis of molybdenum–sulfide gels and aerogels. The MoSx chalcogels have a BET surface area of 353 m2/g and a band gap of 1.5 eV.