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

An orange-yellow vanadomolybdate complex was prepared by heating a 100 mM Mo VI -20 mM V V -0.45 M HCl-20% (v/v) CH 3 CN system at 70 °C for 24 h, being isolated as the tetrapropylammonium (Pr 4 N + ) salt. The Pr 4 N + salt crystallized in the orthorhombic space group P2 1 2 1 2; the lattice constants were a = 18.417(4), b = 20.869(5), c = 15.280(3) A, V = 5873(2)A 3 , and Z=2. The crystallographic study revealed that the structure consists of an α-Wells-Dawson-type [V 2 Mo 18 Ο 62 ] 6- anion, in which vanadates serve as the central tetrahedra. The α-[V 2 Mo 18 O 62 ] 6- complex underwent a two-step one-electron reduction in CH 3 CN, and the presence of acid caused the one-electron waves to be converted into three two-electron waves. The formation conditions were elucidated by 51 V NMR measurements.