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

Two new dinuclear fluoro peroxovanadium(V) complexes, Cs-3[V2O2(O-2)(4)F]center dot H2O (1) and Cs-3[V2O2(O-2)(3)F-3]center dot 2HF center dot 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 mu-eta(1):eta(2) bridging peroxo group, the [V2O2(O-2)(3)F-3](3-)ion in 2 exhibits a symmetrical structure with a unique mu-fluoro and mu-eta(2):eta(2) peroxo 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 V-51 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.