Syntheses,structures, and magnetism of {V15M6O42(OH)6(Cl)} (M = Si,Ge)

Two V₁₅M₆(OH)₆O₄₂(Cl)]^7? (M = Si for 1, Ge for 2) cluster anions with protonated amines as counterions have been synthesized under hydrothermal conditions and characterized by FT-IR, energy dispersive spectroscopy, XPS, powder X-ray diffraction, thermogravimetric analysis (TGA), elemental analysis, and single-crystal X-ray analyses. Both compounds consist of {V₁₅M₆O₄₂(OH)₆(Cl)} (M = Si for 1, Ge for 2), which are derived from {V₁₈O₄₂} by substitution of three {VO₅} square pyramids with three {Si₂O₅(OH)₂/Ge₂O₅(OH)₂} units. It represents the first example of cage-like polyoxovanadates (POVs) containing three (Si/Ge)₂O₅(OH)₂ units. There are extensive hydrogen bonding interactions between POVs and organoamines in 1 and 2. Compound 1 presents a close-packed layer aggregate, while 2 exhibits the packing of six-membered rings with a 1-D channel. Magnetism measurements demonstrate the presence of strong antiferromagnetic interaction between V^IV centers in 1.