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), b ismuth (82% yield), or antimony (97% yield) reduction. A modification of a published procedure for reduction of WCl6 with red phosphorus, wh ich improves (WCl4)(x) purity, is also described. Highly reactive (WCl 4)(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 yi elds to the known WCl4(MeCN)(2) and W2Cl4(OMe)(4)(HOMe)(2). The molecu lar structure of (WCl4)(x), as determined by single-crystal X-ray diff ractometry, consists of a polymer of opposite-edge-sharing bioctahedra with alternating short (W(1)-W(1A), 2.688(2) Angstrom) and long (W(1) ... W(1B), 3.787(3) Angstrom) tungsten-tungsten distances. The acute W (1)-Cl(2)-W(1A) angle (69.4(2)degrees), obtuse Cl(1)-W(1)-W(1A) angle (94.99(12)degrees), short axial Cl(1)... Cl(1A) nonbonded distance (3. 085(10) Angstrom, substantially less than twice the Cl van der Waals r adius); and short W(1)-W(1A) distance are consistent with a strong W(1 )-W(1A) interaction best described as a W=W bond for this d(2)-d(2) co mpound. Crystal data: Cl4W, a = 11.782(3) Angstrom, b = 6.475(1) Angst rom c = 8.062(2) Angstrom, beta = 131.14(1)degrees, V = 463.2(2) Angst rom(3), monoclinic, C2/m, Z = 4.