The ring opening polymerization reaction of tetrahydrofuran (thf) by WCl6 was investigated under different conditions, and the polymeric material was characterized by NMR and SEC (Size Exclusion Chromatography) analyses. The mixed valence complex [(thf)(2)(mu-H)][{WOCl3(thf)}(2)(mu-O)], 3, was isolated from the reactions of WCl6 with 4-8 equivalents of thf in dichloromethane at room temperature, and crystallographically characterized. The formation of 3 was preceded by that of WOCI4(thf), 2, while Cl (CH2)(4)Cl and Cl(CH2)(4)O(CH2)(4)Cl were identified as the prevalent organic side products. The 1:1 M reaction of WCl6 with meO(CH2)(2)OH, in CH2Cl2 at room temperature, afforded the complexes (WOCl4)(2)(mu-kappa(2)-1,4-dioxane), 4, and WCl5(O...