Two Hexa-Ni-Substituted AsWO Clusters Functionalized by Organic Ligands.

Hydrothermal reactions of trilacunary precursor A- α-AsWO polyoxoanions and nickel ions in the presence of ethylenediamine (en = ethylenediamine) led to two new hexa-Ni-substituted Keggin-type tungstoarsenates [Ni( μ-OH)(en)(HO)(B- α-AsWO)]·6HO ( 1) and [Ni( μ-OH)(en)(HO)(B- α-AsWO)]·10HO ( 2), which have been characterized by elemental analyses, IR spectra, powder X-ray diffraction, thermogravimetric analyses and single-crystal X-ray diffraction. Crystal data for 1: hexagonal, R3 c, a = b = 20.4379(5) Å, c = 21.5062(6) Å, β = 120º, V = 7779.8 (3) Å and Z = 6; for 2: momoclinic, P2/ c, a = 13.4200(3) Å, b = 19.1428(5) Å, c = 22.8845(9) Å, β = 112.403(3)º, V = 5435.2(3) Å and Z = 4. Structural analyses reveal that the [Ni( μ-OH)(B- α-AsWO)] clusters in 1 and 2 are covalently functionalized by neutral en ligands, in which two similar {Ni( μ-OH)(en)(HO)} cores have been observed by our lab. Notably, 1 and 2 represent the highest number of substituted transition metal ions in all known lacunary Keggin-type polyoxotungstoarsenate monomers. [ABSTRACT FROM AUTHOR]