The alkoxides of zirconium and hafnium: direct electrochemical synthesis and mass-spectral study. Do ''M(OR)4'', where M = Zr, Hf, Sn really exist?

Article abstract of DOI:10.1007/BF00698513

The direct electrochemical synthesis of zirconium (1a) and hafnium (1b) alkoxides, M(OPrⁱ)4*PrⁱOH, Zr(OBuⁱ)4'BuⁱOH (4a) and M(OR)4, where R = Et (2a,b), n-Bu (3a), s-Bu (5a), C2H4OMe (6a,b) has been carried out by anodic oxidation of metals in anhydrous alcohols in the presence of LiCl as a conductive additive to give quantitative yields.The solubility polytherms and dissociation pressure of 1a,b have been investigated.It has been proved by means of chemical analysis, X-ray powder, and IR spectral studies that the desolvation of 1a,b and Sn(OPrⁱ)4*PrⁱOH (1c) is accompanied by the formation of amorphous oxocompounds M3O(OPrⁱ)10.On the basis of 1H NMR data it has been proved that the structure of the latter is analogous to that of known triangular cluster molecules M3(μ3-O)(μ3-OR)(OR)6, where M = Mo, W, U.Mass-spectral data and the determined physicochemical characteristics of 1-5 permit to conclude that the samples of composition M(OR)4, where M = Zr, Hf, and 2, 3, 5 contain tri- and tetranuclear oxocomplexes M3O(OR)10 and M4O(OR)14 respectively, along with Zr(OR)4 oligomers of different molecular complexity. - Key words: oxoalkoxides, zirconium and hafnium alkoxides, electrochemical synthesis, mass-spectra, IR-, NMR-spectral, X-ray powder analysis.