Silver Vanadyl(IV) ortho-Pyrophosphate: Synthesis, Crystal Structure, and Characterization of the (V≡O)2+ Group.

Ag6(VIVO)2(PO4)2(P27) was obtained by reaction of Ag3PO4 and (VO)2P2O7 (sealed ampoule, 550 °C, 3 d). The crystal structure of the new mixed ortho-pyrophosphate was determined from X-ray single-crystal data [Pnma, Z = 4, a = 12.759(3) Å, b = 17.340(4) Å, c = 6.418(1) Å, R1 = 0.071, wR2 = 0.184 for 3174 unique reflections with F0 > 4σ(F0), 141 variables]. Ag+ ions are located in between layers [(VIVO)2(PO4)2(P2O7)]6-. Equilibrium relations of the new phosphate to neighboring phases were determined. The electronic structure of the (VIV≡O)2+ group was investigated by polarized electronic absorption spectroscopy (ν1a = 9450 cm-1, ν1b = 9950 cm-1, ν2 = 14750 cm-1), EPR spectroscopy [X- and Q-band, powder and single crystal, orthorhombic crystal g-tensor with g1 = 1.9445(3), g2 = 1.9521(3), g3 = 1.9695(3)] and magnetic measurements (powder, μexp/μB = 1.71, Θp = -1.7 K). [ABSTRACT FROM AUTHOR]