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

New molybdenum thiochlorides, α-MoSCl 3 and β-MoSCl 3, have been synthesized by chemical vapor transport. A selenium analog, MoSeCl 3, 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 [Mo 2 (S 2 )Cl 4 Cl 4/2 ] runs along the crystallographic c axis, while for the β- phase ∞ 1 [Mo 2 (S 2 )Cl 3 Cl 6/2 ] chain passes through the b -axis. MoSeCl 3 is isostructural to α-MoSCl 3 . The formal charge on molybdenum in these thiochlorides have been assigned by X-ray photoelectron spectroscopy (XPS) to be +IV. β-MoSCl 3 and already known Mo 3 S 7 Cl 4 and MoS 2 Cl 3 are weakly paramagnetic. Thermal decomposition of molybdenum thiochlorides leads to MoS 2 . Red MoS 2 Cl 3 and Mo 3 S 7 Cl 4 exhibit band gaps of ∼2.07 and ∼2.11 eV, while black α-MoSCl 3, β-MoSCl 3, and MoSeCl 3 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 MoS x chalcogels have a BET surface area of 353 m 2 /g and a band gap of 1.5 eV.