Facile Reduction of Tungsten Halides with Nonconventional, Mild Reductants. 2. Four Convenient, High-Yield Solid-State Syntheses of the Hexatungsten Dodecachloride Cluster W(6)Cl(12) and Cluster Acid (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)(), Including New Cation-Assisted Ternary Routes.
Tungsten hexachloride was reduced by Hg or Bi at moderately low temperatures ( approximately 350 degrees C) to afford good yields (Hg, 73%; Bi, 85%) of W(6)Cl(12) after conversion of the reduction product to the chloro acid (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(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 (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)() from WCl(6) reduction by Sb improved dramatically to 79% with added KCl, while LiCl reduced the yield to only traces. In Bi reduction of WCl(6), the yield of (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(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 (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)() and W(6)Cl(12).
Kolesnichenko
Vladimir
V
Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242.
Messerle
Louis
L