Facile Reduction of Tungsten Halides with Nonconventional, Mild Reductants. I. Tungsten Tetrachloride:  Several Convenient Solid-State Syntheses, a Solution Synthesis of Highly Reactive (WCl₄)_x, and the Molecular Structure of Polymeric Tungsten Tetrachloride

Polymeric (WCl4)x has been prepared in crystalline form from WCl6 by three new, safer solid-state approaches via mercury (in 83% yield), bismuth (82% yield), or antimony (97% yield) reduction. A modification of a published procedure for reduction of WCl6 with red phosphorus, which improves (WCl4)x purity, is also described. Highly reactive (WCl4)x powder can be prepared in 99% yield via tin reduction of WCl6 in 1,2-dichloroethane. (WCl4)x powder was readily converted in high yields to the known WCl4(MeCN)2 and W2Cl4(OMe)4(HOMe)2. The molecular structure of (WCl4)x, as determined by single-crystal X-ray diffractometry, consists of a polymer of opposite-edge-sharing bioctahedra with alternating short (W(1)−W(1A), 2.688(2) A) and long (W(1)···W(1B), 3.787(3) A) tungsten−tungsten distances. The acute W(1)−Cl(2)−W(1A) angle (69.4(2)°), obtuse Cl(1)−W(1)−W(1A) angle (94.99(12)°), short axial Cl(1)···Cl(1A) nonbonded distance (3.085(10) A, substantially less than twice the Cl van der Waals radius), and short W(1...