Crystal structure of the heptamolybdate(VI)(paramolybdate) ion, [Mo7O24]6–, in the ammonium and potassium tetrahydrate salts
01 Jan 1975-Journal of The Chemical Society-dalton Transactions (The Royal Society of Chemistry)-Iss: 6, pp 505-514
TL;DR: In this article, the crystal structures of the isomorphous salts MI6[Mo7O24],4H2O (M = NH4 or K) have been refined by three-dimensional X-ray diffraction methods.
Abstract: The crystal structures of the isomorphous salts MI6[Mo7O24],4H2O (M = NH4 or K) have been refined by three-dimensional X-ray diffraction methods. Unit cell dimensions of these monoclinic compounds, space group P21/C with Z= 4, are, ammonium salt: a= 8·3934 ± 0·0008, b= 36·1703 ± 0·0045, c= 10·4715 ± 0·0011 A, β= 115·958°± 0·008°; and potassium salt: a= 8·15 ± 0·02, b= 35·68 ± 0·1, c= 10·30 ± 0·02 A, β= 115·2°± 02°.By use of multiple Weissenberg patterns, 8197 intensity data (Mo-Kα radiation) for the ammonium compound and 2178 (Cu-Kα radiation) for the potassium compound were estimated visually and used to test and refine Lindqvist's proposed structure in the space group P21/c. Lindqvist's structure was confirmed and the full matrix least-squares isotropic refinement led to R 0·076 (ammonium) 0·120 (potassium), with direct unambiguous location of the cations and water molecules in the potassium compound.
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TL;DR: In this paper, the preparation of a colloidal colloidal by un procede sol gel is described, and a procedure for determination des proprietes electriques et electrochimiques is described.
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TL;DR: The Anderson-Evans archetype is a highly flexible POM cluster that allows modification from several point-of-views; it can incorporate a large number of different heteroatoms differing in size and oxidation state, and can incorporate inorganic and organic cations and molecules demonstrating different coordination motifs, and covalent attachment with tris(hydroxymethyl)methane ligands allows it to be combined with specific organic functionalities as mentioned in this paper.
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TL;DR: In this paper, the Anderson-type molybdopolyanions containing tris(alkoxo) ligands [MMo6O18{(OCH2)3CR}2]3− (M = NiII, ZnII), (R = CH3, NO2, CH2OH), were prepared by treatment of [N(C4H9)4]4] 4[α-Mo8O26] with trishydroxymethylmethane derivatives in the presence of manganese(III) acetyl
Abstract: Anderson-type molybdopolyanions containing tris(alkoxo) ligands [MMo6O18{(OCH2)3CR}2]3− (M = MnIII, FeIII) and [H2MMo6O18{(OCH2)3CR}2]2− (M = NiII, ZnII), (R = CH3, NO2, CH2OH), were prepared by treatment of [N(C4H9)4]4[α-Mo8O26] with tris(hydroxymethyl)methane derivatives in the presence of manganese(III) acetylacetonate, iron(III) acetylacetonate, nickel(II) acetate, or zinc(II) acetate. The complexes were structurally characterized in solution, and also by single-crystal X-ray diffraction in the cases of [N(C4H9)4]3[MnMo6O18{(OCH2)3CNO2}2], [N(C4H9)4]2[H2NiMo6O18{(OCH2)3CCH2OH}2], and [N(C4H9)4]2[H2ZnMo6O18{(OCH2)3CCH3}2]. Two tris(alkoxo) ligands replace the six hydroxo groups usually found in Anderson polyanions of formula [H6MMo6O24]n−. The complex structures may be divided into two groups: In the first one the tris(alkoxo) ligands are bound entirely to the central heteroatom, while in the second one they cap a tetrahedral cavity. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)
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TL;DR: The chemistry of isopolymolybdates and isopolytungstates has been an area of intense activity for several decades as discussed by the authors, and it is hardly surprising that not a single textbook correctly describes the situation in acidified molybdate and tungstate solutions.
Abstract: Publisher Summary The chemistry of isopolymolybdates and isopolytungstates has been an area of intense activity for several decades. Yet, even today one cannot claim that all the important processes occurring on acidification of a molybdate or tungstate solution have been elucidated. Numerous contradictory reports appearing in the literature right up to the present have repeatedly done more to confuse than to clarify the subject. Thus, it is hardly surprising that not a single textbook correctly describes the situation in acidified molybdate and tungstate solutions. The number of proposals for polyions occurring in such solutions is legion. With little exaggeration it may be said that there is no conceivable species that has not been proposed at some time or other. Much of the effort involved in this field consists in scrutinizing the experimental conditions, the evaluation of measurements, and the interpretations given in past and present publications. The large number of methods already used in these studies presents a further difficulty.
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