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 VIV centers in 1.