Inorganic Chemistry, Vol.37, No.15, 3660-3663, 1998
Facile reduction of tungsten halides with nonconventional, mild reductants. 2. Four convenient, high-yield solid-state syntheses of the hexatungsten dodecachloride cluster W6Cl12 and cluster acid (H3O)(2)[W-6(mu(3)-Cl)(8)Cl-6](OH2)(x), including new cation-assisted ternary routes
Tungsten hexachloride was reduced by Hg or Bi at moderately low temperatures (similar to 350 degrees C) to afford good yields (Hg, 73%; Bi, 85%) of W6Cl12 after conversion of the reduction product to the chloro acid (H3O)(2)[W-6(mu(3)-Cl)(8)-Cl-6](OH2)(x), recrystallization, and thermolysis in vacuo. Antimony was a less effective reductant because of the lower yield of chloro acid (31%) and the substantial quantities of insoluble byproducts found after HCl workup. The yield of (H3O)(2)[W-6(mu(3)-Cl)(8)Cl-6](OH2)(x) from WCl6 reduction by Sb improved dramatically to 79% with added KCl, while LiCl reduced the yield to only traces. In Bi reduction of WCl6, the yield of (H3O)(2)[W-6(mu(3)-Cl)(8)Cl-6](OH2)(x) decreased from 86 to 49% upon addition of NaCl, whereas added KCl had no effect on the yield. The Hg-, Bi-, Sb/KCl-, and Bi/KCl-based routes offer substantial experimental advantages over published methods for preparation of (H3O)(2)[W-6(mu(3)-Cl)(8)Cl-6](OH2)(x) and W6Cl12.