Synthesis and Structural Characterization of Non-Homoleptic Carbamato Complexes of VVand WVIand Their Facile Implantation onto Silica Surfaces

The vanadium(V) amido-carbamato derivatives VO(NR2)(O2CNR2)2(R = Me, 1; Et, 2) are obtained by the reaction of VOCl3with preformed carbamato species (ammonium or sodium carbamates). The synthesis of an ionic ammonium chlorido-amide of WVI, 3, is performed using WOCl4and diethylamine as precursors. Moreover, the reactivity of 3 with CO2is investigated. Mixed WVIchlorido-carbamato compounds, 4 and 5, are obtained by the reaction of WOCl4with stoichiometric amounts of sodium diethylcarbamate. All of the products are characterized by analytical and spectroscopic methods (IR spectroscopy, multinuclear NMR spectroscopy) and by X-ray diffraction in the cases of 3 and 4. DFT calculations are useful to elucidate the structures of the compounds and to give insight into the various reaction pathways. The combination of 2 or 5 with amorphous silica gives solid materials, which are characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and energy dispersive X-ray spectroscopy (EDS) coupled to scanning electron microscopy (SEM).