Dinuclear fluoro-peroxovanadium(v) complexes with symmetric and asymmetric peroxo bridges: syntheses, structures and DFT studies

Abstract

Two new dinuclear fluoro peroxovanadium(V) complexes, Cs₃[V₂O₂(O₂)₄F]·H₂O (1) and Cs₃[V₂O₂(O₂)₃F₃]·2HF·H₂O (2), were prepared and characterized by elemental analysis, IR spectroscopy, thermal analysis and X-ray crystallography. While the anion in 1 possesses an asymmetric structure with a μ-η¹:η² bridging peroxo group, the [V₂O₂(O₂)₃F₃]³⁻ ion in 2 exhibits a symmetrical structure with a unique μ-fluoro and μ-η²:η²peroxo double bridge. The X-ray structure data were compared with equilibrium and vibrationally-averaged (effective) DFT calculated geometries. The decomposition reactions of 1 and 2 in aqueous solution were studied by ⁵¹V NMR spectroscopy. The calculations of vibrationally averaged NMR chemical shifts (DFT-GIAO) were used to support the empirical assignment of NMR signals and afforded excellent agreement with experimental values for the studied peroxovanadium species. The ESI mass spectra of the prepared compounds are in accordance with the assignment of NMR spectra and with DFT study.