The first transition metal iodato peroxido complex: the synthesis, vibrational spectra and crystal structure from powder diffraction data of K 3 [V 2 O 2 (O 2 ) 4 (IO 3 )]·H 2 O

The first transition metal iodato peroxido complex, K 3 [V 2 O 2 (O 2 ) 4 (IO 3 )]·H 2 O ( I ), was prepared by crystallization from the KVO 3 — KIO 3 — H 2 O 2 — H 2 O — ethanol (HNO 3 ) solution. The dinuclear anion is immediately decomposed in aqueous solution; the 51 V NMR spectrum exhibits signals corresponding to [VO(O 2 ) 2 (H 2 O)] − , [V 2 O 2 (OH)(O 2 ) 4 ] 3− and H 2 VO 4 − species only. The IR and Raman spectra contain all characteristic bands of the VO(O 2 ) 2 group and the coordinated IO 3 − ligand. Based on the positions of bands assigned to the vibrations of the VO(O 2 ) 2 groups a pentagonal pyramidal arrangement around the vanadium atoms can be supposed. The crystal structure was solved from X-ray synchrotron powder data by direct space method and refined by energy minimization in the solid state employing a hybrid PBE0 functional. This crystal and molecular structure, has confirmed the presence of hexacoordinated vanadium atoms and revealed asymmetric dinuclear structure of the [V 2 O 2 (O 2 ) 4 (IO 3 )] 3− ion. The coordination spheres of vanadium atoms are different — the IO 3 − anion is coordinated only to one vanadium center. A thermal analysis of the complex confirmed the presence of water molecules in the crystal structure and revealed a considerable stability of the dehydrated complex.