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Conditions are determined for the formation of sodium heteropolyhexamolybdenumnickelate(II) Na[Ni(OH)MoO]•16HO ( I) in a Ni(NO)-NaМоO-HNO-HO solution acidified to Z = = ν(H)/ν(МоO) = 1.00. Synthesized salt I is investigated by chemical analysis, single crystal XRD, powder XRD, thermal analysis, and IR spectroscopy. The heteropolyanion is shown to belong to the Anderson type. Compound I is analyzed by single crystal XRD ( M = 1404.61, triclinic, space group $$P\bar 1$$, a = 8.0586(4) Å, b = 10.5445(6) Å, c = 12.1374(5) Å, α = 69.557(5)°, β = 70.604(4)°, γ = 84.123(4)°, V = 911.45(8) Å) to find that it is isostructural to Na[Ni(OH)MoO]•16HO. All metal atoms in the structure of I are in an octahedral environment: the coordination sphere of the Ni heteroatom consists of OH groups; that of Mo consists of O atoms and OH groups; Na atoms are linked to the heteropolyanion via the terminal O atoms of the polyanion and surrounded by water molecules. In the crystal packing, the [Ni(OH)MoO] anions lie in planes parallel to $$(1\bar 10)$$ and the polyanion layers alternate with those formed by the paired octahedra [Na(μ-HO)(HO)(O)] in the direction of the y axis. [ABSTRACT FROM AUTHOR]

The green crystals of Ni1.5H[Ni(OH)6W6O18]·12.5H2O and blue crystals of Na4[Ni(OH)6W6O18]·16H2O were isolated from the acidified (to Z = ν(H+)/ν(WO) = 1.00) solutions of Ni(NO3)2-Na2WO4-HNO3-H2O systems. The synthesized salts were identified by chemical analysis, XRPA, and IR spectroscopy. It was shown that the heteropolyanions belonged to the Anderson-Evans type of structure. An X-ray diffraction study of Na4[Ni(OH)6W6O18]·16H2O was carried out ( Mr = 1932.07, triclinic, space group P-1, a = 8.0089(11) Å, b = 10.5758(14) Å, c = 12.1987(16) Å; α = 69.268(13)°, β = 71.069(12)°, γ = 83.816(11)°; V = 914.0(2) Å3 at T = 293 K, Z = 1, ρcal = 3.510 g/cm3, F000 = 874, μ = 19.470 mm−1, −16 ≤ h ≤ 16, −21 ≤ k ≤ 21, −24 ≤ l ≤ 24; the final R factors are RF = 0.0277, wR2 = 0.0469 for the observed reflections ( RF = 0.0606, wR2 = 0.0523 for all independent reflections); S = 0.953; CSD-419883). The structure was solved by direct methods and refined in an anisotropic approximation. Hydrogen atoms were found in a difference synthesis and refined in an isotropic approximation with geometrical limitations. The nature of water in Na4[Ni(OH)6W6O18]·16H2O was characterized by DTA. XRPA was used to identify the thermolysis products of heteropoly compounds. [ABSTRACT FROM AUTHOR]