Reactivity of [WCl6] with Ethers: A Joint Computational, Spectroscopic and Crystallographic Study

The reactions of [WCl6] with a series of ethers have been performed in chlorinated solvent and elucidated by means of analytical, spectroscopic and DFT methods. The addition of tetrahydropyran (thp) or 1,4-dioxane to [WCl6] resulted in the reversible formation of the adducts WCl6 center dot center dot center dot L [L = thp (1a), 1,4-dioxane (1b)], detected in solution by NMR spectroscopy. The reaction of [WCl6] with thp in a molar ratio of 1:2 in chloroform at reflux afforded [WOCl4(thp)] (2a), which was isolated in 51% yield. [WOCl4(OMe2)] (2b) and [WOCl3(OMe2)(2)] (3a) were isolated in yields of 53 and 18%, respectively, from the reaction of [WCl6] with an excess of dimethyl ether. [WOCl3(OEt2)(2)] (3b) was the only identified metal compound produced from the reaction of [WCl6] and OEt2 (1:2 molar ratio). According to NMR studies, the oxide ligand in 2a,b and 3a,b was generated by double C-O bond cleavage involving one equivalent of organic reactant. The 1:1 reaction of [WCl6] with 1,2-diethoxyethane led to [WCl5(kappa(1)-OCH2CH2OEt)] (4) and a minor amount of [WCl4(kappa(2)-EtOCH2CH2OEt)] (5). The aryl oxide compound [WCl5(OPh)] (6) was prepared in 62% yield from the reaction of [WCl6] and anisole by selective C-sp3-O bond activation. The prolonged heating of a mixture of [WCl6] and diphenyl ether in 1,2-dichloroethane led to the isolation of the W-V complex [WCl5(OPh2)] (7). The molecular structures of 2a and 3a were ascertained by X-ray diffraction.