Preparation and Characterization of an α-Wells–Dawson-Type [V2Mo18O62]6−Complex

Abstract An orange-yellow vanadomolybdate complex was prepared by heating a 100 mM MoVI–20 mM VV–0.45 M HCl–20% (v/v) CH3CN system at 70 °C for 24 h, being isolated as the tetrapropylammonium (Pr4N+) salt. The Pr4N+ salt crystallized in the orthorhombic space group P21212; the lattice constants were a=18.417(4), b=20.869(5), c=15.280(3) Å, V=5873(2) Å3, and Z=2. The crystallographic study revealed that the structure consists of an α-Wells–Dawson-type [V2Mo18O62]6− anion, in which vanadates serve as the central tetrahedra. The α-[V2Mo18O62]6− complex underwent a two-step one-electron reduction in CH3CN, and the presence of acid caused the one-electron waves to be converted into three two-electron waves. The formation conditions were elucidated by 51V NMR measurements.