Novel Mixed-Valence Heteropolyoxometalates: A Molybdenum Diphosphonate Anion [MoV7MoVIO16(O3PPhPO3H)4]3- and Its One- and Two-Dimensional Assemblies

A novel mixed-valence polyoxomolybdenum anion, [MoV7MoVIO16(O3PPhPO3H)4]3-, was synthesized hydrothermally from molybdenum oxide, molybdenum metal, boric and phosphoric acids, 1,2-phenyldiphosphonic acid, and imidazole (ImH) and was structurally characterized as an imidazolium salt (orthorhombic, Aba2; a = 16.674(4), b = 17.238(1), and c = 24.81(2) (angstrom)). One- and twodimensional structures of this anion and additional molybdenum diphosphonate linkers were assembled as well. They were structurally characterized as their pyridinium (pyH) salts (pyH)4[{MoV7MoVIO16(O3PPhPO3)2(O3PPhPO3H)2}{Mo2O4(OH)(HO3PPhPO3H)}]·5H2O (monoclinic, P21/c; a = 20.8506(9), b = 22.866(1), and c = 21.1403(9) (angstrom); (beta)= 118.7087(8) °) and (pyH)3[{MoV7MoVIO16 (O3PPhPO3)4}{Mo2O2(OH)2(HO3PPhPO3H)}]·3H2O (orthorhombic, Pca21; a = 19.057(1), b = 20.402(2), and c = 20.660(2) (angstrom)). The compounds were also characterized by IR spectroscopy and magnetic measurements.