Half-sandwich metal diselenolate complexes Cp#M(NO)(SePh)2 (M = Mo or W; Cp# = Cp or MeCp) as ligands. Synthesis of selenolate-bridged heterobimetallic compounds

The reactions of half-sandwich diselenolate Mo and W complexes Cp^#M(NO)(SePh)₂ (M = Mo; Cp^# = Cp (1a), MeCp (1b); M = W; Cp^# = Cp (1c)) with (Norb)Mo(CO)₄, Ni(COD)₂ and Fe(CO)₅ have been investigated. Treatment of (1a), (1b) and (1c) with (Norb)Mo(CO)₄ in PhMe gave the bimetallic complexes: CpMo(NO)(-SePh)₂Mo(CO)₄ (2a), MeCpMo(NO)(-SePh)₂Mo(CO)₄ (2b) and CpW(NO)(-SePh)₂Mo(CO)₄ (2c) in moderate yields. Irradiation of (1a) and (1c) in the presence of Fe(CO)₅ gave heterobimetallic complexes CpMo(CO)(-SePh)₂Fe(CO)₃ (3a) and CpW(NO)(-SePh)₂Fe(CO)₃ (3c). Ni(COD)₂ reacts with two equivalents of (1a), (1b) and (1c) to give [CpMo(NO)(-SePh)₂]₂Ni (4a), [MeCpMo(NO)(-SePh)₂]₂Ni (4b) and [CpW(NO)(-SePh)₂]₂Ni (4c) in good yields. The new heterobimetallic complexes were characterized by i.r., ¹H-n.m.r., ¹³C-n.m.r. and EI-MS spectroscopy.     

Order and disorder in mixed metal linear chains: The homo and heterobimetallic EDTA (M(H2O)4OIOII)[M′(EDTA)] · 6H2O complexes (M = Mg,Mn, Co,Zn and Ni; M′ = Co,Ni, Cu and Zn)

Summary Polymetallic solid solutions of the ethylenediaminetetracetic acid (EDTA) and six divalent metal ions exist in the range: MgMnCoZnNiCu(EDTA) · 6H₂O where + + + + + =2, 01, 0,,2, 0, 1.This type of structure is characterized by the presence of two different octahedral carboxylate-bridged coordination sites forming infinite zig-zag chains. Visible and i.r. spectra and t.g.a. analysis show that there is occupational preference for the two coordination sites in the crystalline structure.Due to this preference, and also to the structural features, the heterobimetallic MM(EDTA) · 6H₂O compounds constitute a structurally new class of materials which can be described as ordered alternating-heterobimetallic polymeric coordination complexes.     

On the crystal chemistry of three copper(II)-arsenates: Cu3(AsO4)2-III,Na4Cu(AsO4)2, and KCu4(AsO4)3

The three copper(II)-arsenates were synthesized under hydrothermal conditions; their crystal structures were determined by single-crystal X-ray diffraction methods:Cu₃(AsO₄)₂-III:a=5.046(2) Å,b=5.417(2) Å,c=6.354(2) Å, =70.61(2)°, =86.52(2)°, =68.43(2)°,Z=1, space group ,R=0.035 for 1674 reflections with sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a=4.882(2) Å,b=5.870(2) Å,c=6.958(3) Å, =98.51(2)°, =90.76(2)°, =105.97(2)°,Z=1, space group ,R=0.028 for 2157 reflections with sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a=12.234(5) Å,b=12.438(5) Å,c=7.307(3) Å, =118.17(2)°,Z=4, space group C2/c,R=0.029 for 1896 reflections with sin / 0.80 Å^–1.Within these three compounds the Cu atoms are square planar [4], tetragonal pyramidal [4+1], and tetragonal bipyramidal [4+2] coordinated by O atoms; an exception is the Cu(2)^[4+1] atom in Cu₃(AsO₄)₂-III: the coordination polyhedron is a representative for the transition from a tetragonal pyramid towards a trigonal bipyramid. In KCu₄(AsO₄)₃ the Cu(1)^[4]O₄ square and the As(1)O₄ tetrahedron share a common O—O edge of 2.428(5) Å, resulting in distortions of both the CuO₄ square and the AsO₄ tetrahedron. The two Na atoms in Na₄Cu(AsO₄)₂ are [6] coordinated, the K atom in KCu₄(AsO₄)₃ is [8] coordinated by O atoms.Die drei Kupfer(II)-Arsenate wurden unter Hydrothermalbedingungen gezüchtet und ihre Kristallstrukturen mittels Einkristall-Röntgenbeugungsmethoden ermittelt:Cu₃(AsO₄)₂-III:a = 5.046(2) Å,b = 5.417(2) Å,c = 6.354(2) Å, = 70.61 (2)°, = 86.52(2)°, = 68.43(2)°,Z = 1, Raumgruppe ,R = 0.035 für 1674 Reflexe mit sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a = 4.882(2) Å,b = 5.870(2) Å,c = 6.958(3) Å, = 98.51(2)°, = 90.76(2)°, = 105.97(2)°,Z = 1, Raumgruppe ,R = 0.028 für 2157 Reflexe mit sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a = 12.234(5) Å,b = 12.438(5) Å,c = 7.307(3) Å, = 118.17(2)°,Z = 4, Raumgruppe C2/c,R = 0.029 für 1896 Reflexe mit sin / 0.80 Å^–1.Die Cu-Atome in diesen drei Verbindungen sind durch O-Atome quadratisch planar [4], tetragonal pyramidal [4 + 1] und tetragonal dipyramidal [4 + 2]-koordiniert; eine Ausnahme ist das Cu(2)^{[4 + 1]}-Atom in Cu₃(AsO₄)₂-III: Das Koordinationspolyeder stellt einen Vertreter des Übergangs von einer tetragonalen Pyramide zu einer trigonalen Dipyramide dar. In KCu₄(AsO₄)₃ haben das Cu(1)^[4]O₄-Quadrat und das As(1)O₄-Tetraeder eine gemeinsame O—O-Kante von 2.428(5) Å, was eine Verzerrung der beiden Koordinationsfiguren CuO₄-Quadrat und AsO₄-Tetraeder bedingt. Die zwei Na-Atome in Na₄Cu(AsO₄)₃ sind durch O-Atome [6]-koordiniert, das K-Atom in KCu₄(AsO₄)₃ ist [8]-koordiniert.

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Zur Kristallchemie dreier Kupfer (II)-Arsenate: Cu₃(AsO₄)₂-III, Na₄Cu(AsO₄)₂ und KCu₄(AsO₄)₃

     

Preparation and structure of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with 3-amino-5-(α/β)pyridyl-1, 2, 4-triazoles

Summary Complexes of bidentate 3-amino-5-()-pyridyl-1,2,4-triazole (L¹) and 3-amino-5-()-pyridyl-1, 2, 4-triazole (L²) of composition [ML¹Cl₂·H₂O], [ML²Cl₂·H₂O], [ML ₃ ^2/1 Cl₂] and [ML ₃ ^2/2 Cl₂] [M=Co^II, Ni^II, Cu^II, M=Zn^II] have been prepared and characterized by elemental analyses, i.r., u.v./visible, e.s.r. spectra, magnetic moments and molar conductances.     

Darstellung,Thermisches Verhalten und Gitterparameter von Erbiumfluorooxalattetrahydrat ErFC2O4 · 4H2O

Zusammenfassung Erbiumfluorhydrat ErF₃ · 1.1 H₂O bildet in Oxalsäurelösungen Erbiumfluorooxalattetrahydrat ErFC₂O₄ · 4 H₂O. Das ErFC₂O₄ · 4 H₂O ist grobkristallin, unlöslich in verdünnten Säuren und Laugen und löslich in konzentrierter Schwefelsäure. Beim thermogravimetrischen Abbau bildet es die Verbindungen ErFC₂O₄ · 2 H₂O, ErFC₂O₄ · · H₂O, ErFC₂O₄, ErOF und ErO_1.5. Die Kristallstruktur des ErFC₂O₄ · 4 H₂O ist orthorhombisch mit den Gitterkonstantena=11.217±0.007 Å,b-13.046±0.008 Å,c=9.191±0.005 Å undZ=6.

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Erbium fluoride hydrate ErF₃ · 1.1 H₂O forms in solutions of oxalic acid erbium fluorooxalate tetrahydrate ErFC₂O₄ · 4 H₂O. The ErFC₂O₄ · 4 H₂O is coarse-crystalline, insoluble in diluted acids and bases and soluble in concentrated sulphuric acid. During thermal decomposition ErFC₂O₄ · 2 H₂O, ErFC₂O₄ · H₂O, ErFC₂O₄, ErOF and ErO_1.5 are formed. The crystal structure of ErFC₂O₄ · 4H₂O is orthorhombic, with lattice constantsa=11.217±0.007 Å,b=13.046±0.008, Å c=9.191±±0.005Å andZ=6.

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Résumé Le fluorure d'erbium hydraté (ErF₃ · 1.1 H₂O) forme dans l'acide oxalique fluorooxalate d'erbium tétrahydraté (ErFC₂O₄ · 4 H₂O), un précipité consistant à gros cristaux insoluble dans les acides et bases dilués, mais soluble dans l'acide sulfurique concentré. Au cours de sa décomposition thermique on obtient ErFC₂O₄ · 2 H₂O; ErFC₂O₄ · H₂O; ErFC₂O₄, ErOF et ErO_1.5. ErFC₂O₄ · 4 H₂O a une structure cristalline ortorhombique avec les paramètres suivants:a=11.217±0.007 Å,b=13.046±0.008 Å,c-9.191 ±0.005 Å,Z=6.

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ErF₃ · 1.1 H₂O, ErFC₂O₄ · 4H₂O. ErFC₂O₄ · 4H₂O, - , , . : ErFC₂O₄ · 2H₂O. ErFC₂O₄ · H₂O, ErFC₂O₄, ErOF ErO_1·5. ErFC₂O₄ · 4 H₂O a=11,217±0,007 Å,b=13,046±0,008 Å,c=9,191± 0,005 Å Z=6.

     

Synthesis,Structure, and Magnetic Properties of the Silicides <Emphasis Type="BoldItalic">RE</Emphasis>IrSi (<Emphasis Type="Italic">RE</Emphasis> = Ce,Pr, Er,Tm, Lu) and SmIr<Subscript>0.266(8)</Subscript>Si<Subscript>1.734(8)</Subscript>

Summary. The equiatomic rare earth metal–iridium–silicides REIrSi (RE=Ce, Pr, Er, Tm, Lu) were prepared by arc-melting of the elements and subsequent annealing. All silicides were characterized through their X-ray powder patterns. The structures of CeIrSi, ErIrSi, and LuIrSi were refined from X-ray single crystal diffractometer data: LaIrSi type, P2₁3, a=629.15(2)pm, wR2=0.1232, 280F² values, and 11 variable parameters for CeIrSi; TiNiSi type, Pnma, a=673.4(1), b=416.07(5), c=744.88(9)pm, wR2=0.0705, 339F² values, and 20 variable parameters for ErIrSi, and a=664.0(3), b=412.9(1), c=742.6(1)pm, wR2=0.0398, 496F² values, and 20 variable parameters for LuIrSi. The iridium and silicon atoms in CeIrSi, ErIrSi, and LuIrSi build three-dimensional [IrSi] networks where the iridium atoms have three (CeIrSi, Ir–Si 229pm) and four (ErIrSi, Ir–Si 247–258pm; LuIrSi, Ir–Si 245–256pm) silicon neighbors. The [IrSi] networks leave larger channels in which the cerium, erbium, and lutetium atoms are located. Temperature dependent susceptibility data for LuIrSi indicate Pauli paramagnetism. CeIrSi shows Curie-Weiss paramagnetism above 100K with an experimental magnetic moment of 2.56(2)_B/Ce atom. With samarium as rare earth metal component the silicide SmIr_0.266(8)Si_1.734(8) with -ThSi₂ type structure was obtained: I4₁/amd, a=409.3(1), c=1397.2(5)pm, wR2=0.0575, 161F² values, and 9 variable parameters. Within the three-dimensional [Ir_0.266Si_1.734] network the Ir/Si–Ir/Si distances range from 230 to 237pm.     

Novel dioximato-bridged chromium(III)-copper(II)-chromium(III) trinuclear complexes with ferromagnetic exchange interactions

Summary Two new dioximato-bridged trinuclear Cr^II-Cu^II-Cr^III complexes, [Cr(salen)-Cu(-BD)₂-Cr(salen)] (1) and [Cr(salen)-Cu(-FD)₂-Cr(salen)]-H₂O (2), have been prepared and characterized [salen^2– = N,N-ethylene- bis (salicylideneiminate), (-BD)^2– = -benzyldioximato and (-FD)^2– = -furildioximato]. Magnetic susceptibility measurements in the 4.2–300 K range demonstrated the operation of a ferromagnetic interaction between the adjacent Cr^III and Cu^II ions through oximato bridges in both (1) and (2). Based on spin Hamiltonians =–2J(₁₂+₂₃)(S₁=S₃=3/2,S₂=1/2) the exchange integrals (J) were evaluated as 3.19 and 5.38 cm^–1 for (1) and (2), respectively.     

MIITiO(C2O4)2·4H2O (MII=Mg,Ca, Sr OR Ba) as precursors in the formation of MIITiO3 powders

A synthesis route is described for the preparation of the alkaline earth metal titanyl oxalates M^IITiO(C₂O₄)₂·4H₂O (M^II=Mg, Ca, Sr or Ba). The thermal decompositions of these compounds were studied by means of DTA and TG in comparison with X-ray measurements. The final products M^IITiO₃ were characterized morphologically.

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Zusammenfassung Ein Syntheseweg für die Darstellung der Erdalkalimetalltitanyloxalate M^IITiO(C₂O₄),·4H₂O (M ^II=Mg, Ca, Sr, Ba) wird beschrieben. Die thermische Zersetzung dieser Verbindungen wurde mittels DTA und TG sowie Röntgenbeugungsmethoden untersucht. Die entstehenden Titanate M^IITiO₃ wurden hinsichtlich ihrer morphologischen Eigenschaften charakterisiert.

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- MⁱⁱTiO(C₂O₄)₂ · 4₂, ⁱⁱ = , , . , . ⁱⁱiO₃, .

     

Pressure effects on aminonaphthalene dye fluorescence in H2O and D2O

The pressure dependence of excited-state proton transfer equilibria has been examined for aqueous solutions of several substituted napthalene dyes, in particular 1-dimethylaminonaphthalene-5-sulfonic acid (DANS). The pressure-induced shift in equilibrium is characterized by volume changes spanning the range V ^*=–18 cm³ mole^–1 to V ^*=+4 cm³-mole^–1. A deuterium oxide solvent isotope effect is evident in the pressure response of DANS, leading to a 35% smaller V_* in D₂O relative to H₂O.     

Synthesis and thermal decomposition of (NH4)2[MIIIF5(H2O) (M=Al,Fe and Cr)

Ammonium pentafluorometallate monohydrates were prepared by different methods and characterized by chemical analysis, IR spectrometry and X-ray diffraction. Unit cell parameters were determined for the Fe and Cr compounds, which were found to be isostructural with the known Al compound. The IR spectra, X-ray diffraction patterns and lattice data on the compounds are very similar, and point to the existence of isolated [M^IIIF₅(H₂O)]^2– octahedra. The water is coordinated to theM ^III cation.Dehydration and thermal decomposition were investigated by thermal analysis (TG, DTG, DTA) on the Q-derivatograph and by high-temperature X-ray diffraction. Different dehydration temperatures and products were found, depending on the nature of theM ^III cation. NH₄F is liberated in several steps (Al or Fe) or continuously (Cr), leading to the formation ofM ^III fluorides.

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Zusammenfassung Ammoniumpentafluormetallat-monohydrate (NH₄)₂MeF₅ · H₂O (M=Fe, Al, Cr) wurden nach verschiedenen Methoden präpariert und durch chemische Analyse, IR-Spektren und Röntgenbeugung charakterisiert. Die Elementarzellen-Parameter der mit der Al-Verbindung isostrukturellen Fe- und Cr-Verbindung wurden ermittelt. IR-Spektren, Röntgenbeugungsdiagramme und Gitterdaten aller drei Verbindungen sind einander sehr ähnlich und beweisen das Vorliegen isolierter [M^IIIF₅(H₂O)]^2– -Oktaeder, in denen Wasser mit dem Kation koordiniert ist. Entwässerung und thermische Zersetzung wurden durch simultane TG-DTG-DTA und durch Hochtemperatur-Röntgenbeugung untersucht. Abhängig vom KationM ^III werden unterschiedliche Reaktionsprodukte und -temperaturen gefunden. Unter kontinuierlicher (M=Cr) oder schrittweiser Freisetzung von NH₄F (Fe, Al) wird das jeweilige Fluorid M^IIIF₃3 gebildet.

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, . , , . , . [M^IIIF₅(H₂O)]^2–, ^III. Q- , , . , M^III. , , — , .

     

Synthesis and spectroscopic studies of complexes containing the Schiff base 1-acetylferrocene(thio)semicarbazone

Summary [RuCl₂(CO)₂] _n reacts with the Schiff base 1-acetylferrocenethiosemicarbazone, [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)] to give [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)RuCl₂(CO)₂] and with 1-acetylferrocenesemicarbazone [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)] to give [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)RuCl₂-(CO) ₂]. Spectroscopic data indicate that the Schiff bases act as bidentate ligands and coordinate to ruthenium via the hydrazinic N and either the S or O atoms, respectively, giving stable heterobimetallic complexes, which have been characterized by i.r. and ¹H-n.m.r. spectroscopies, and elemental analyses.Part of this work was presented at the First International Conference in Chemistry and its applications in Doha, Qatar, 1993.     

Dehydration of lithium triphosphate pentahydrate,Li5P3O10· 5H2O

The kinetics of isothermal-isobaric dehydration of Li₅P₃O₁₀·5H₂O in vacuum (p=10^–1 hPa) and in water vapour atmosphere ( =23·hPa) was investigated by TG in the temperature range 40–140°. It was shown that the initial non-degradation removal of 1/10 of the crystal water, the rate of which is sensitive to , proceeds according to the laws of reversible topochemical reactions. In the next, irreversible degradation stage, where the bulk of the crystal water is removed, the kinetic characteristics of the process and the DSC effects exhibit a low sensitivity to the water vapour pressure. The peculiarities of Li₅P₃O₁₀·5H₂O dehydration were considered in comparison with the thermal behaviour of Na₅P₃O₁₀·6H₂O and K₅P₃O₁₀·4H₂O.

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Zusammenfassung Die Kinetik der isotherm-isobaren Dehydratisierung von Li₅P₃O₁₀·5H₂O in Vakuum (p=10^–4 hPa) und in Wasserdampfatmosphäre ( =23 hPa) wurde durch TG im Temperaturbereich von 40–140° untersucht. Es wurde gezeigt, daß die anfängliche, noch keine Zersetzung zur Folge habende Eliminierung von 1/10 des Kristallwassers, deren Geschwindigkeit von abhängt, nach den Gesetzen der reversiblen topochemischen Reaktionen abläuft. Im nächsten irreversiblen Zersetzungsschritt, in dem die Hauptmenge des Kristallwassers austritt, sind die kinetischen Kennwerte des Prozesses und die DSC-Effekte nur wenig vom Wasserdampfdruck abhängig. Die Besonderheiten der Dehydratisierung von Li₅P₃O₁₀·5H₂O werden im Vergleich mit dem thermischen Verhalten von Na₅P₃O₁₀·6H₂O und K₅P₃O₁₀·4H₂O erörtert.

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40–140° - Li₅P₃O₁₀ · 5₂ (=10^–4 ) (=23 ). , 1/10 , . , - . L₅₃₁₀·5₂ Na₅P₃O₁₀·6H₂O K₅₃₁₀·4₂.

     

Synthesis of new dinuclear dicopper(II) and dinickel(II) complexes. The kinetics of catechol oxidase and electrochemistry of a dicopper(II) complex

A new dinuclear ligand L, ethylene[OO-bis-salicylidene--diketone] bearing two symmetrical coordination sites was synthesized by the condensation of salicylaldehyde and acetylacetone, L, with 1,2-dibromoethane under reflux. The ligand L in a 1:1 ratio was treated with CuCl₂ and NiCl₂ to yield the complexes, tetrachloro bis[OO-bis- salicylidene--diketone copper(II)] and bis[OO-bis-salicylidene--diketone nickel(II)] chloride. The complexes were subsequently characterized by spectroscopic techniques, elemental analysis, i.r., ¹H-n.m.r., ¹³C-n.m.r., u.v.–vis., e.p.r. spectroscopy, and conductance measurements. The conductance measurements in DMF reveal that the Cu^II complex is covalent while the Ni^II complex is ionic and the spectral data support the Cu^II complex to be distorted octahedral whereas the Ni^II complex has square-planar geometry. The dioxygen binding was studied spectrophotometrically by the oxidation of tetrachloro bis[OO-bis-salicylidene--diketone copper(II)] with pyrocatechol in the presence of oxygen. The kinetic experiments were performed with the copper complex in DMF by monitoring the increase in absorbance over time at pH 8.0 in the presence of pyrocatechol at 25 °C. The kinetic parameters V_max and K_M were determined on the Michaelis–Menten Approach. Redox behavior of the dinuclear copper(II) complex was investigated by cyclic voltammetry in the presence of O₂ with the pyrocatechol (substrate) and also without the substrate. The large difference in potentials E⁰ is indicative of reversible oxygen binding of the complex and distinct catalytic activity.     

The kinetics of base hydrolysis of [Co(trien)(amine)Cl]2+ complexes (amine=imidazole,pyridine,n-butylamine and 2,2-dimethoxyethylamine)

Summary The complexescis--[Co(trien)(ImH)Cl]²⁺ (ImH=imidazole, trien=1,8-diamino-3,6-diazaoctane),cis--[Co(trien)(Buⁿ-NH₂)Cl^–]²⁺,cis--[Co(trien)(NH₂CH₂-CH(OMe)₂)Cl^–]²⁺ andcis-₂-[Co(trien)(py)Cl]²⁺ (py=pyridine) have been characterised and their kinetics of base hydrolysis studied. Thecis--isomers which have afac-fac arrangement of the trien ligand have values of k _OH ²⁵ in the 73 to 253 dm³ mol^–1 s^–1 range at I=0.1 mol dm^–3. Extremely rapid base hydrolysis is observed withcis-₂-[Co(trien)(py)Cl]²⁺ where k _OH ²⁵ is 6.65×10⁶ mol³ mol^–1 s^–1 at I=0.1 mol dm^–3. This complex has amer-fac arrangement of the trien ligand with flatsec-NH donor leading to rapid base hydrolysis due to good -overlap between the conjugate base and cobalt(III). The pyridine ligand causes aca. 30 fold rate increase compared with the hydrolysis ofcis-₂-[Co(trien)(NH₃)Cl]²⁺.     

Dehydrations of Ca(H2PO4)2·H2O and Mg(H2PO4)2·2H2O and their reactions with KCl,examined with simultaneous TG,DTG, DTA and EGA

The dehydrations of Ca(H₂PO₄)₂·H₂O and Mg(H₂PO₄)₂ H₂O were examined with a simultaneous TG, DTG, DTA and EGA method, partly under conventional, and partly under quasi-isothermal and quasi-isobaric conditions. It was found among others that the dehydrations of the examined compounds took place gradually between 100 and 500°, a series of intermediates being formed. The end-products were [Ca(PO₃)₂]₃ and Mg(PO₃)₂. The reactions of these hydrates with KCl were also examined. The many subsequent part reactions could be described by the following overall equation: 3 Ca(H₂PO₄)₂ + 2 KCl=Ca₂P₂O₇ + Ca(PO₃)₂ + 2 KPO₃ + 2 HCl + 5 H₂O It is noteworthy that the reactions do not lead to the formation of orthophosphates, but stop after the liberation of 2 moles of HCl.

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Zusammenfassung Die Autoren untersuchten die Dehydratisierung von Ca(H₂PO₄)₂·H₂O und Mg(H₂PO₄)₂·2H₂O. Zu den Untersuchungen wurde die simultane Methode von TG, DTG, DTA und EGA teils unter konventionellen, teils unter quasi isothermen und quasi isobaren Bedingungen eingesetzt. Die Autoren fanden u.a., daß die Dehydratisierung der untersuchten Verbindungen zwischen 100 und 500 °C stufenweise verlief, während eine Reihe von Zwischenprodukten gebildet wurde. Die Endprodukte waren [Ca(PO₃)₂]₃ bzw. Mg(PO₃)₂. Die Autoren prüften auch die Reaktion der erwähnten Hydrate mit KCl. Sie fanden, daß die zahlreichen aufeinanderfolgenden Teilreaktionen durch folgende Bruttoreaktion beschrieben werden können: 3Ca(H₂PO₄)₂ + 2KCl=Ca₂P₂O₂ + Ca(PO₃)₂ + 2KPO₃ + 2HCl + 5H₂O. Es ist bemerkenswert, daß die Reaktionen nicht zur Bildung von Orthophosphaten führen, sondern daß sie nach Freisetzung zweier Moleküle von HCl zum Stillstand kommen.

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Résumé Les auteurs ont étudié la déshydratation de Ca(H₂PO₄)₂·H₂O et Mg(H₂PO₄)₂·2 H₂O. Les méthodes de TG, TGD, ATD et AGE on été utilisées simultanément en partie dans les conditions conventionelles et en partie dans les conditions quasi isothermes et quasi isobares. Les auteurs ont trouvé, entre autres, que la déshydratation de ces composés a eu lieu de façon graduelle entre 100 et 500 °C, avec formation d'une série de produits intermédiaires. Les produits finaux sont respectivement [Ca(PO₃)₂]₃ et Mg(PO₃)₂. Les auteurs ont également examiné la réaction des hydrates mentionnés avec KCl. Ils ont trouvé qu'un grand nombre de réactions partielles consécutives peut être décrit par la réaction brute suivante: 3 Ca(H₂PO₄)₂ + 2 KCl=Ca₂P₂O₇ + Ca(PO₃)₂ + 2 KPO₃ + 2 HCl + 5 H₂O. Il est remarquable que les réactions n'entraînent pas la formation d'orthophosphates mais qu'elles s'arrêtent après l'élimination de 2 moles de HCl.

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(₂₄)₂ ·₂ Mg(H₂PO₄)₂ 2H₂O. , , . , 100–500° . , , [(₃)₂]₃ Mg(PO₃)₂. l. , : 3(₂₄)₂ + 2KCl=₂₂₇ + (₃)₂ + 2₃ + 2l + 5₂ , , l.

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The authors wish to thank Prof. E. Pungor for his interest in this work.     

Configurations of the [Pd(NO2)4]2- Complex Anion: Crystal Structure of Ag4A2[M(NO2)4]3 (M = Pd, Pt; A = K, Rb)

An integrated Xray diffraction study was performed on polycrystals and single crystals of three new isostructural phases with general formula Ag₄A₂[M(NO₂)₄]₃ (M = Pd, Pt; A = K, Rb). Data on the crystal structure solution (CAD4 diffractometer, MoK radiation, graphite monochromator = 2–30° are presented. In one crystallographically independent [M(NO₂)₄]^2- complex anion, the planar square coordination of the central atom is completed to 4 + 2 by two oxygen atoms at a distance of 3.02–3.12 in the other anion, it is completed to 4 + 1 + 1 by an oxygen atom at a distance of 3.12–3.30 and an Ag⁺ cation at a distance of 3.04–3.11 . Part of the Ag⁺ cations form Ag - Ag dimers with a distance of 3.03–3.07. Crystalchemical analysis of known structures containing [Pd(NO₂)₄]^2- complex anions was performed. It has been established that in none of the cases do any of the possible limiting configurations occur.     

Molecular and crystal structures of Ph2P(O)(CH2)2OH and Ph2P(O)CH2(C6H6)OH

The molecular and crystal structures of Ph₂P(O)(CH₂)₂OH and Ph₂P(O)CH₂(C₆H₆)OH have been determined. For the first compound the space group is with unit cell dimensions a=10.505(2), b=13.720(2), c=14.782(3) Å; =72.58(6), =76.95(6), =72.49(6)° for Z=6 (Syntex diffractometer,MoK radiation, 2996 reflections, R=3.2%). The second compound crystallizes in the space group P2₁2₁2₁ with unit cell dimensions a=9.371(3), b=9.014(3), c=18.461(5) Å for Z=4 (DAR-UM diffractometer,CuK radiation, 909 reflections, R=4.9%). In Ph₂P(O)(CH₂)₂OH, three independent molecules differing in structural details are linked by the P=O...O hydrogen bonds (O...H is 1.84, 1.80, and 1.86 Å), to form a chain. In Ph₂P(O)CH₂(C₆H₆)OH, the molecules are joined by pairs of the P=O...H–O bonds (O...H is 1.81 Å) to form 16-membered dimeric associates.Institute of Chemical Physics, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 3, pp. 109–118, May–June 1993.Translated by T. Yudanova     

Coordination chemistry of alkali and alkaline earth cations: Synthesis and X-ray crystal structure of cesium (picrate) (benzo-15-crown-5) Cs+C6H2N3O 7 − (C14H20O5)

Crystals of the Cs⁺ Pic^– (B15C5) complex (Pic=picrate; B15C5=benzo-15-crown-5) (M _r =629.3) are yellow prisms which belong to the triclinic space groupP witha=7.377(4),b=11.372(2),c=14.806(2) , =90.31(1), =91.06(2), =108.32(2)⁰,Z=2,D _x =1.77, andD _m =1.77 g cm^–3. FinalR=0.055 for 3575 observed reflections out of a total of 4004 measured reflections. Cesium forms a 1:1 anion paired complex with B15C5 like sodium rather than a charge separated sandwich structure as found for potassium and expected for cesium in view of the ion-cavity radius concept. The Cs cation is 9-coordinate involving the five crown oxygens (Cs...O, 3.00(1) to 3.24(1) ), the phenoxide (Cs...O^–, 3.03(1) ) and anortho nitro group oxygen (Cs...O, 3.01(1) ) of the picrate counteranion and, uniquely, with two additional oxygens (Cs...O, 3.17(1) and 3.40(1) ) from apara nitro group of the picrate belonging to the adjacent molecule in the lattice. The Cs⁺ ion lies 2.07 out of the mean plane formed by the crown oxygens. This system provides the first structural evidence that the interaction stoichiometry of an alkali cation with a cyclic multidentate ligand is not a function of the ion and cavity size alone but also of its Lewis acid strength as modified by the charge neutralizing anion. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82027.     

Kinetics of the thermal decompositions of MC2O4 to MCO3 (M=Ca,Sr AND Ba)

The kinetics of the thermal decompositions of CaC₂O₄, SrC₂O₄ and BaC₂O₄ to their carbonates were studied by thermogravimetry at constant and at linearly increasing temperatures. Isothermally, the three oxalates decompose according to A_1.43, R_1.54 and R₁ laws, respectively. Dynamically, the decompositions of the first two oxalates proceed in a similar way as under the isothermal conditions, whereas BaC₂O₄ decomposes according to a different law.Kinetic compensation laws were established for the decomposition of CaC₂O₄ and SrC₂O₄ under both isothermal and non-isothermal conditions. Such a compensation law is considered to result if correct kinetic model functionsF () are used when the isothermal and non-isothermal decompositions are regulated by the sameF().

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Zusammenfassung Die Kinetik der thermischen Zersetzung von CaC₂O₄, SrC₂O₄ und BaC₂O₄ zu den entsprechenden Carbonaten wurde durch Thermogravimetrie bei konstanter und linear ansteigender Temperatur untersucht. Isotherm werden die drei Oxalate entsprechend A_1.43, R_1.54 bzw. R₁ zersetzt. Dynamisch verläuft die Zersetzung der ersten zwei Oxalate auf ähnlichem Wege, während BaC₂O₄ nach einem davon verschiedenem Gesetz abgebaut wird. Kinetische Kompensationsgesetze wurden sowohl unter isothermen als auch unter nicht-isothermen Bedingungen für die Zersetzung von CaC₂O₄ und SrC₂O₄ ermittelt. Ein solches Kompensationsgesetz wird als Ergebnis eines solchen Vorgehens angesehen, bei dem richtige kinetische ModellfunktionenF() benutzt werden, wenn die nicht-isothermen Zersetzungen durch die gleichenF() bestimmt sind.

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- , . , , A_1.43, R_1.54 · R₁- , . , . F() «» , F().

     

Triterpene glycosides ofHedera canariensis. I. Structures of glycosides L-A,L-B1, L-B2, L-C,L-D,L-E1 1, L-G1, L-G2, L-G3, L-G4, L-H1, L-H2, AND L-I1 from the leaves ofHedera canariensis

From the leaves of Algerian ivyHedera canariensis Willd. (fam. Aralaceae) we have isolated 13 triterpene glycosides: the 3-O--L-arabinopyranosides of oleanolic acid (A), of echinocystic acid (B₁), and of hederagenin (B₂); the 3-O-[O--L-rhamnopyranosyl-(2)--L-arabinopyranoside]s of oleanolic acid (C), of echinocystic acid (D), and of hederagenin (E₁); the 3-O--L-rhamnopyranoside] 28-O-[O--L-rhamnopyranosyl-(14)--gentiobioside of hederagenin (G₁); the 3-O-[O--L-rhamnopyranosyl-(12)--L-arabinopyranoside] 28-O--gentiobioside of hederagenin (G3); the 3-O-[O--L-rhamnopyranosyl-(12)--L-arabinopyranoside] 28-O-[O--L-rhamnopyranosyl-(14)--gentiobioside]s of oleanolic acid (G₂), of echinocystic acid (H₁), and of hederagenin (H₂); the 3-O-[O--L-rhanmopyranosyl-(12)--D-glucopyranoside] 28-O-(O--L-rhamno-pyranosyl-(14)--gentiobioside] of hederagenin (H₂); and the 3-O-(O--L-rhamnopyranosyl-(12)-O-gentiobiosyl)-O-(14)--L-rhamnopyranosyl-(12)-a-L-arabinopyranoside] of hederagenin (G₄). The structures of the substances isolated have been established on the basis of chemical transformations and¹³C NMR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 377–383, May–June, 1996. Original article submitted December 3, 1995.