CRYSTAL-STRUCTURE AND VIBRATIONAL-SPECTRA OF NA2VO(SO4)2

Blue crystals of the compound Na2VO(S4)2 suitable for X-ray structure determination have been obtained by dissolving V2O5 in molten Na2S2O7 at a temperature of 400 °C and bubbling a 10% SO2–90% N2 gas mixture through the solution. In a few hours, blue needle-shaped crystals precipitated. The unique crystal structure belongs to the orthorhombic system in space group P212121 (No. 19), with a = 6.303 (1) Å, b = 6.803 (1) Å, c = 16.682 (2) Å, and Z = 4. The structure consists of sodium ions and a three-dimensional network of vanadyl ions (VO2+), interlinked by two kinds of bridging sulfate ions. Sulfate coordinates to the vanadium unidentately, forming a distorted VO6 octahedron with one V–O bond length of 1.595 (2) Å, four in-plane bonds between 2.01 and 2.07 Å, and one bond opposite to the short one, with a length of 2.150 (2) Å. The O–V–O angles are distorted from 90° by less than 12°. The sulfate groups are slightly deformed and tilted, in such a way that the V–O–S bond angles are around 130 ± 3°. Short sodium-oxygen contacts (2.35–2.41 Å) are encountered. Sulfate groups 1 and 2, respectively, contain one (O(7)) and two (O(8) and O(9)) oxygen atoms, which are uniquely bound by short bonds to S(1) and S(2), respectively. Infrared and Raman spectra of the compound have been recorded and interpreted. © 1990, American Chemical Society. All rights reserved.