In powder mixtures of ZnO and Ti02 the compounds Zn2Ti04, ZnTiO3 and Zn2Ti308 can be formed as a result of solid state reactions. The mechanism of the double oxide formation is essentially determined by the microstructure of the powder mixture. Furthermore, the kind of the double oxide depends on the TiOrmodification. There exist structural similarities between Zn2TiOc (spinel) and Ti02 (anatase) on the one hand and ZnTiO3 and Ti02 (rutile) on the other hand. The compound ZnzTisOa is formed only on the basis of the ZnzTiO4-phase. The crystal structure of Zn2Ti308 was derived as a defect spinel. The unoccupied sites of cations are not arranged statistically, but they areprdered in the structure. This order leads to the decrease of the space group symmetry from Fd-3m to P4332.In Pulvermischungen aus ZnO und Ti02 konnen Zn2Ti04, ZnTiOs and Zn2Ti308 entstehen. Der Mechanismus der Doppeloxidbildung wird wesentlich durch die Mikrostruktur der Pulvermischung bestimmt. Die Art des Doppeloxides hangt auhrdem von der Struktur der TiOrModifikation ab. Zwischen Zn2TiO4 (Spinell) und Ti02 (Anatas) einerseits und ZnTiO3 und Ti02 (Rutil) andererseits bestehen strukturelle Gemeinsamkeiten. Die Verbindung ZnzTi308 wird nur uber die Zwischenphase ZnzTiO4 gebildet. Die Kristallstruktur der Verbindung ZnzTi308 wurde als ein Defektspinell abgeleitet. Die unbesetzten Kationenpliitze liegen nicht ' statistisch, sondern geordnet i n der Struktur vor. Die Ordnung fiihrt zu einer Erniedrigung der Raumgruppensymmetrie von Fd-3m auf P4332.
The tautomerism of eight benzofuroxans has been studied by proton magnetic resonance a t low temperatures. Theequilibrium constants implied small (0-500 cal./mole) energy differences, and indicated that electron-acceptor groups favoured the 6-position and electron-donor groups the 5-position. The activation energies for the equilibrations were in the region of 14 kcal./mole. NUCLEAR MAGNETIC RESONANCE spectroscopy has established the structure of benzofuroxan as a rapidlyequilibrating system between benzofurazan 1-and 3oxides (I + 11; R = H), probably via the intermediate o-dinitrosobenzene (111) .2-6 The activation energy (estimated at ca. 15 kcal./mole3) for the equilibration is such that the aromatic protons show coalescence temperatures near 5" , averaging chemical shifts of ca. 8 ~. / s e c .~ 4-Nitrobenzofuroxan shows a single ABC spectrum a t all temperatures, indicating that one form, presumably represented by formula (IV; R = NO,), predominates to the extent that the alternative 3-oxide structure is undetectable at the low temperatures required to " freeze " the equilibrium on the n.m.r. time-scale. In the case of the corresponding 5-substituted derivative, however, both 5-nitro-(I) and 6nitro-(11; R = NO,) structures are present, the spectrum a t -31" indicating that ca. 70% of (11) exists with ca. 30% of (I) in the equilibrium r n i x t~r e .~ Other benzofuroxans which have been studied by n.m.r. at low temperatures include the 5,6-dinitr0-,~~7,8 5,6-di-~h l o r o -,~ 4,7-dichloro-,9 4,7-dibromo-,79 and &methyl-7 compounds.
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RThe equilibrium between (I) and (11) appears to provide a direct comparison between the electronic properties of the nitrogen atom (position 3) and the N-oxide group (position 1) of the benzofuroxan system. At first sight, it might be supposed that both electron-5 G. Englert, 2. anulyt.
Bei der Reaktion von wäßrigen NH4HPO3F‐ bzw. sauren (NH4)2PO3F‐Lösungen mit Kupfer(II)‐Salzen wird unter Zusatz von Aceton bzw. Ethanol als Fällungsmittel Kupfer(II)‐monofluorophosphat‐Dihydrat CuPO3F · 2H2O 1 als kristalliner Niederschlag gebildet. Aus 1 läßt sich durch thermische Entwässerung wasserfreies Kupfer(II)‐monofluorophosphat CuPO3F 2 herstellen.
1 kristallisiert in der monoklinen Raumgruppe P21/c mit a = 761,44, b = 780,97, c = 921,02 pm, β = 112,94° und Z = 4.
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