Tungsten(VI) alkoxides cannot be prepared by the metathesis reaction of WCl6 with alkyl alcohols - unlike tungsten phenoxide W(OPh)6 : the reason is that such reaction results in a reduction to W(V).
Thus, tungsten(VI) alkoxides must be prepared from tungsten hexakis(dimethylamide) [W(NMe2 )6 (complicated because the most efficient synthesis of [W(NMe2)6] from WBr6 and [LiNMe2] has a yield of only 16 %): W(NMe2)6 + 6 ROH -> W(OR)6 + 6 HNMe2
Tungsten hexamethoxide [W(OMe)6 ] (M=, ) is solid.
Synthesis and characterisation of tungsten hexamethoxide (as well as several other tungsten (VI) alkoxides has been described by Bradley et al. The obtained [W(OMe)6] was characterized by several physicochemical studies (including infrared and Raman spectroscopy). [[i][PS1] ]
W(NMe2)6 + 6 MeOH -> W(OMe)6 + 6 HNMe2 (hexane, RT)
[W(OMe)6] has been also obtained by electrochemical synthesis (anodic oxidation/dissolution of tungsten metal in MeOH), followed by fractional crystallization from the obtained electrolytes). [W(OMe)6] has been crystallographically: the symmetrically independent units in the structure of [W(OMe)6], follow the C1 (slightly distorted D2d) symmetry (isomorphous to Mo(OMe)6). Crystal data for W(OMe)6 at 22 degrees C, a = 7.1164(19), b = 6.6414(18), and c = 12.304(3) A, beta = 90.047(5) degrees, V = 581.5(3) A3, monoclinic P2/n, Z = 2. [[ii][PS2] ]
The molecular structure of [W(OMe)6] in the gasphase was studied by gas electron diffraction, the most suitable model has been determined [[iii]]
[W(OMe)6] can be potentially applied as precursor for the deposition of WO3 films by AACVD, MOCVD or ALD.
[i] D. C. Bradley, M. H. Chisholm, M. W. Extine, and M. E. Stager, Inorg. Chem. 1977, 16, 7, 1794–1801, “Some reactions of hexakis(dimethylamido)tungsten(VI)”, https://doi.org/10.1021/ic50173a044, https://pubs.acs.org/doi/pdf/10.1021/ic50173a044
[ii] G.A. Seisenbaeva, L. Kloo, P. Werndrup, V.G. Kessler, Inorg. Chem., 2001; 40(15):3815-8, doi: 10.1021/ic0013173, « Electrochemical synthesis, X-ray single crystal, IR spectroscopic, and quantum chemical investigation of molybdenum and tungsten hexamethoxides », https://pubmed.ncbi.nlm.nih.gov/11442382/
[iii] A.Haaland, K. Rypdal, H .V. Volden, E. Jacob, J. Weidlein, Acta Chemica Scandinavica, p.911-913, DOI number: 10.3891/acta.chem.scand.43-0911, « The Molecular Structure of Tungsten Hexamethoxide, W(OCH3)6, by Gas Electron Diffraction »