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

Ag₆(V^IVO)₂(PO₄)₂(P₂O₇) 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 F_o > 4σ(F_o), 141 variables]. Ag⁺ ions are located in between layers [(V^IVO)₂(PO₄)₂(P₂O₇)]^6–. Equilibrium relations of the new phosphate to neighboring phases were determined. The electronic structure of the (V^IV≡O)²⁺ group was investigated by polarized electronic absorption spectroscopy (ν̃_1a = 9450 cm^–1, ν̃_1b = 9950 cm^–1, ν̃₂ = 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, μ_exp/μ_B = 1.71, Θ_p = –1.7 K).