Vanadium forms several oxides with a wide variety of properties and technological applications in the fields of catalysis, solid-state batteries, electrochromic devices, and infrared modulators. [1][2][3][4] The ability of vanadium atoms to possess multiple oxidation states, and the facile conversion between oxides of different stoichiometry, makes the synthesis of pure vanadium oxide phases complicated. [5,6] Divanadium pentaoxide (V 2 O 5 ) and vanadium dioxide (VO 2 ) are the two main oxide phases, and several chemical and physical methods have been used to obtain such oxides. [6][7][8][9][10][11] Among vapor phase techniques CVD offers the opportunity of preparing metal oxide films with good quality and uniformity. [6,9,12] In the CVD of vanadium oxide, VO [16] The best synthetic way consisted in reacting VCl 3 Ã 3THF with Na(OCMe 2-CH 2 OMe) in THF, prepared in-situ from the corresponding alcohol MeOCH 2 CMe 2 OH and Na, at a temperature below À78 8C. After the work-up, a 20% yield of pure [V(OCMe 2-CH 2 OMe) 3 ], as a violet oil, was recovered by sublimation. The complex was characterized by elemental analysis and electron impact mass spectrometry (EIMS).The EI spectrum (see Table 1) is characterized by the presence of the molecular peak M þ (m/z ¼ 360) in 12% relative abundance.The structure of the alcohol, which allows both chelation with the metal and transfers of part of the molecule to the metal, and the presence of the electron-donating methoxy groups, help in stabilizing different ions; the most abundant ions corresponding to species orginated by the loss of at least one alkoxide group.The peaks at 315 m/z (rel. abun. 33%) and at 257 m/z (rel. abun. 97%) can be easily ascribed to the species The other quite abundant peaks at 140 m/z (rel. abun. 88%) and 125 m/z (rel. abun. 95%) are from fragments which contain only part of an alkoxide group; it is reasonable to suppose that, like most of the fragments, they keep a VO 2 core, which is promising for the deposistion of VO x of the desired stoichiometry. We tentatively suggest that the ion at 140 m/z is a radical cationic hydroxy species with the formula [V(OH)OC 4 H 7 ] þ , and the ion at 125 m/z is a vanadyl species with the formula [V(O)OC 3 H 6 ] þ . The second part of the work consisted of using the complex as the precursor for the MOCVD of vanadium oxide films by means of a horizontal, hot-wall reactor set at 550 8C, and using N 2 as the carrier gas and a mixture of O 2 and H 2 O as the reactant gas.First, by setting the flow rate of the reactant gas at 400 sccm we were able to grow vanadium dioxide on Si(100) (sample A) and on fused silica glass substrates (sample A 0 ) in the same run; sample A, which was closer to the entrance