Hydrothermal synthesis, crystal structure and magnetic characterization of three hexa-M substituted tungstoarsenates (M = Ni, Zn and Mn)

Three novel hexa-transition-metal complexes substituted tungstoarsenates, [Ni6(imi)6(B-α-H3AsW9O33)2]·2H2O (1), [Zn6(imi)6(B-α-H3AsW9O33)2]·2H2O (2) and [Mn6(imi)6(B-α-H3AsW9O33)2]·4H2O (3) (imi = imidazole), have been synthesized hydrothermally without using any polyoxoanion as precursor and characterized by elemental analyses, IR, TG and X-ray single-crystal diffraction. Compounds 1–3 are isostructural, composed of [B-α-H3AsW9O33]12− anions and [M6(imi)6]12+ complex cations (M = Ni, Zn and Mn), all M atoms are square pyramidal geometry, and held together to form hexagonal metallocycles by edge-sharing oxygen atoms. In compounds 2 and 3, [M6(imi)6(B-α-AsW9O33)2] (M = Zn, Mn) segments act as 12-connected nodes to form complicated 3D network via hydrogen-bonding interactions, respectively. Magnetic measurements for 1 show the presence of ferromagnetic interactions within the hexanuclear Ni2+ cations.