Die Schwingungsspektren einiger kristalliner Dekavanadate

The infrared andRaman spectra of Ba₃V₁₀O₂₈·19 H₂O has been recorded and an assignement for the internal vibrations of the V₁₀O ₂₈ ^6– anion is given. Infrared data of the hydrated decavanadates of silver, cadmium, magnesium and lanthanum are also reported and briefly discussed.

     

Über einige Eigenschaften von Zinkphosphiten mit Berücksichtigung ihrer Wasserstoffbrückenbindung

Zinc phosphites ZnPHO₃·2.5 H₂O, Zn₂H₂P₃H₃O₉·H₂O, Zn₃H₄P₅H₅O₁₅·1.5 H₂O, ZnH₂H₂P₂H₂O₆ have been studied at higher temperatures and by X-rays and molecular spectroscopy. Hydrates ZnPHO₃·2.5 H₂O and Zn₂H₂P₃H₃O₉·H₂O, when heated, yield an anhydrous salt. Thermal decomposition of dihydrogen triorthophosphite and tetrahydrogen pentaorthophosphite leads, before oxidation of the anion, to a mixture of zinc phosphite ZnPHO₃ and dihydrogen diorthophosphite ZnH₂P₂H₂O₆ and then after loss of water of constitution dihydrogen diorthophosphite converts to zinc diphosphite ZnP₂H₂O₅. The results of the thermal decomposition study were confirmed by X-ray investigation. Anhydrous zinc dihydrogen triorthophosphite Zn₂H₂P₃H₃O₉ and zinc diphosphite ZnP₂H₂O₅ were hitherto unknown. Infrared spectra confirmed the existence of hydrogen bonding in all the phosphites studied and in the case of zinc phosphite ZnPHO₃·2.5 H₂O exhibited a symmetry decrease of the anion PHO₃ ^2– from the point group C_3v to C_s. In the crystal lattice of ZnPHO₃·2.5 H₂O hydrogen bonding by water molecules participates, with polyorthophosphites hydrogen bonding shares in the production of anions and in the case of their hydrates there is in addition hydrogen bonding by water molecules.

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Mit 3 Abbildungen     

Raman spectroscopic study of four isotopically substituted lithium hydroxide monohydrates

Raman spectral data of polycrystals of four isotopically substituted lithium hydroxide monohydrates,⁶LiOH·H₂O,⁷LiOH·H₂O,⁶LiOD·D₂O and⁷LiOD·D₂O, have been investigated in the 4,000–50 cm^–1 region. The observed spectra have been analyzed and discussed taking into account the results of the factor group analysis and the H/D and⁶Li/⁷Li isotope effects on the fundamental wavenumbers.

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Raman-spektroskopische Untersuchung von vier isotopisch substituierten Lithiumhydroxid-Monohydraten

Zusammenfassung Raman-spektroskopische Daten von⁶LiOH·H₂O,⁷LiOH·H₂O,⁶LiOD·D₂O und⁷LiOD·D₂O werden im Bereich von 4000 bis 50 cm^–1 angegeben. Die beobachteten Spektren werden analysiert und im Hinblick auf Faktorgruppenanalyse und auf die Isotopeneffekte H/D und⁶Li/⁷Li diskutiert.

     

Der Einfluß großer Salzkonzentrationen auf die Oxydationsreaktion von Fe(phen) 3 2+ mit Ce(IV) in Schwefelsäure

The influence of NaClO₄, NaCl and Na₂SO₄ on the oxidation of Fe(phen) ₃ ²⁺ by Ce(IV) was investigated by means of the stopped-flow method. At the concentrations range of NaClO₄ and NaCl 0.1–1.0M the rate constant values decrease from 1.03·10⁵ to 0.56·10⁵M^–1s^–1 and from 1.08·10⁵ to 0.81·10⁵M^–1s^–1 respectively.In varying concentrations of Na₂SO₄ solutions (0.05–0.35M) the rate constant values decrease from 1.05·10⁵M^–1s^–1 to 0.45·10⁵M^–1s^–1.Taking into account the negative salt effect the mechanism of the reaction progress is proposed.

     

Hydration of the carboxylate group: Anab initio molecular orbital study of acetate-water complexes

The hydration of the carboxylate group in the acetate anion has been investigated by performingab initio molecular orbital calculations on selected conformers of complexes with the form CH₃CO₂ ^– ·nH₂O·mH₂O, wheren andm denote the number of water molecules in the first and second hydration spheres around the carboxylate group, andn + m 7. The results of RHF/6–31G^* optimizations for all the complexes and MP2/6–31+G^** optimizations for several one-water complexes are reported. The primary consequence of hydration on the structure of the acetate anion is a decrease in the length of the C-C bond. Enthalpy and free energy changes calculated at the MP2/6–31+G^** and MP2/6–311+ +G^** levels are reported for the reactions CH₃CO₂ ^– + [H₂O] _P CH₃CO₂ ^– ·nH₂O ·mH₂O where [H₂O] _P is a water cluster containingp water molecules andp=n+m 7. The calculations show that conformers with the lowest enthalpy change on complex formation are often not those with the lowest free energy change, due to a greater entropic loss in complexes with tighter and more favorable enthalpic interactions. Hydrogen bonding of six water molecules directly to the carboxylate group in CH₃CO₂ ^– is found to account for approximately 40% of the enthalpy change and 37% of the free energy change associated with bulk solvation.     

Preparation and study of rare earth 4-aminosalicylates

Summary p-Aminosalicylates of Y, La and lanthanides prepared in the reaction of the ammoniump-aminosalicylate and lanthanide chlorides in solutions have the general formulaLn(C₇H₆O₃N)₃·nH₂O, wheren=3 for La, Ce;n=2 for Pr, Nd, Sm, Eu;n=0 for Y, Gd—Lu. Their solubilities in water are of the order of 10^–3 mol dm^–3. Heating above 350–450 K leads to dehydration and decomposition at the same time. The IR and X-ray spectra for the obtained complexes were recorded. It was found that only complexes of La—Nd are crystalline compounds. The way of metal-ligand coordination is discussed.

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Darstellung und Charakterisierung der Komplexe von Seltenen Erdmetallen mitp-Aminosalicylsäure

Zusammenfassung Zur Darstellung der Verbindungen des TypsLn(C₇H₆O₃N)₃·nH₂O (mitn=3 für La, Ce;n=2 für Pr, Nd, Sm, Eu;n=0 für Y, Gd—Lu) wurde die berechnete Menge von Ammonium-p-aminosalicylat undLnCl₃-Lösungen beipH5.8 gemischt und zur Kristallisation gebracht. Ihre Wasserlöslichkeit bei 298 K ist in der Größenordnung 10^–3 mol dm^–3. Beim Erhitzen erfolgt bei 350–450 K Entwässerung und Zersetzung zugleich. Die Infrarot- und Röntgenspektren der erhaltenen Komplexe wurden gemessen und dabei festgestellt, daß nur die La—Nd-Komplexe kristalline Verbindungen sind. Die Art der Koordination der Seltenerdmetalle mit den Liganden wird diskutiert.

     

Crystal structure and spectra of the Ni(II) complex of pyridine-2,6-dithio-carbomethylamide

The crystal structure of the paramagnetic bis(pyridine-2,6-dithiocarbomethylamide) nickel(II) nitrate (NiPDTA) is described: C₁₈H₂₂N₆S₄·(NO₃)₂·(H₂O)_1,5, monoclinic, C2/c,Z=4,a=14.705 (3) Å,b=23.254 (8) Å,c=8.383 (3) A, =98.18 (2)°,d _x=1.55 gcm^–3,d _m=1.53 gcm^–3. The structure was solved withPatterson and differenceFourier techniques and refined to a residual ofR=0.053. The nickel is surrounded by a square bipyramidal coordination of four thioamide sulfur atoms and two pyridine nitrogen atoms. Vibrational and electronic band positions for this compound are discussed.

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Kristallstruktur und Spektren des Pyridin-2,6-dithiocarbomethylamid Nickel(II)-Komplexes

Zusammenfassung Die Kristallstruktur des paramagnetischen bis(Pyridin-2,6-dithiocarbomethylamid) Nickel(II)-nitrats (NiPDTA) wurde bestimmt. C₁₈H₂₂N₆S₄Ni·(NO₃)₂·(H₂O)_1,5, monoklin, C2/c,Z=4,a=14,705 (3) Å,b=23,254 (8) Å,c=8,383 (3) A, =98,18 (2)°,d _x=1,55gcm^–3,d _m=1,53gcm^–3. Das Phasenproblem wurde mittelsPatterson-und Differenz-Fourier-Synthese bestimmt und die Struktur bis zu einem kristallographischenR-Faktor vonR=0.053 verfeinert. Das Nickel-Atom ist von vier Thioamid-Schwefelatomen und zwei Pyridin-Stickstoffatomen in quadratisch-bipyramidaler Anordnung umgeben. Schwingungsspektren und Anregungsspektren des Komplexes werden diskutiert.

     

Infrared spectra (700–200 cm−1) and6Li/7Li and H2O/D2O isotope effects for four isotopically substituted lithium formate monohydrates

The infrared spectra, in the 700–200 cm^–1 region, have been reported for⁶LiHCO₂ · H₂O,⁶LiHCO₂ · D₂O,⁷LiHCO₂ · H₂O and⁷LiHCO₂ · D₂O and the observed fundamental bands have been discussed taking into account the⁶Li/⁷Li and H₂O/D₂O isotope wavenumber shifts on the fundamental vibrations.

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Infrarotspektren (700–200 cm^–1) und⁶Li/⁷Li- und H₂O/D₂O-Isotopeneffekte für vier isotopensubstituierte Lithiumformat-monohydrate

Zusammenfassung Die Infrarotspektren in der Region von 700–200 cm^–1 werden für⁶LiHCO₂ · H₂O,⁶LiHCO₂ · D₂O,⁷LiHCO₂ · H₂O und⁷LiHCO₂ · D₂O angegeben und die beobachteten Grundschwingungen zusammen mit den isotopischen Verschiebungen der Wellenzahlen diskutiert.

     

Metavanadates and dihydrogendecavanadates with cations of macrocyclic tetraamines

Summary From the reaction systemsCyclam/Mecyclam-KVO₃-H₂O-HCl-EtOH (Cyclam=1,4,8,11-tetraazacyclotetradecane; Mecyclam=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane), the first polyvanadates with cations of macrocyclic amines were isolated: (CyclamH₂)₂-H₂V₁₀O₂₈·2H₂O, (MecyclamH₂)₂H₂V₁₀O₂₈·6H₂O, (CyclamH₂)(VO₃)₂·3H₂O, (CyclamH₂)(VO₃)₂·2H₂O, and (MecyclamH₂)(VO₃)₂·H₂O. The metavanadates with theCyclamH ₂ ²⁺ cation differ markedly in their IR spectra, obviously due to the different structure of the polyanion. The interruption of dynamic heating at the thermal analysis of the crystallohydrates of dihydrogendecavanadates resulted in the formation of corresponding anhydrous dihydrogendecavanadates.

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Metavanadate und Dihydrogendecavanadate mit Kationen aus makrocyclischen Tetraaminen

Zusammenfassung Aus demCyclam/Mecyclam-KVO₃-H₂O-HCl-EtOH Reaktionssystem (Cyclam=1,4,8,11-tetraazacyclotetradecane;Mecyclam=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetrazacyclotetradecane) wurden die ersten Polyvanadate mit cyclischen Aminen als Kationen isoliert: (CyclamH₂)₂V₁₀O₂₈·H₂O, (MecyclamH₂)₂H₂V₁₀O₂₈·6H₂O, (CyclamH₂)(VO₃)₂·3H₂O, (CyclamH₂)(VO₃)₂·2H₂O und (MecyclamH₂)(VO₃)₂·H₂O. Die zwei Metavanadate mit dem KationCyclamH ₂ ²⁺ unterscheiden sich wesentlich in ihren Infrarotspektren, was auf unterschiedliche Polyanionstruktur der Metavanadate hinweist. Durch Unterbrechen der dynamischen Erhitzung bei der thermischen Analyse von Kristallhydraten der Dihydrogendekavanadate wurden entsprechende Verbindungen ohne Kristallwasser gewonnen.

     

Elektrometrische Untersuchungen von Uranylarseniten

Zusammenfassung Mit Hilfe der pH- und konduktometrischen Titrationen wurde die Stöchiometrie der Verbindungen untersucht, die bei der Reaktion von Uranylnitrat mit Alkali-Ortho-, Pyro- und Metaarseniten entstehen. Der Verlauf der Titrationskurven zeigt klar die Bildung der Verbindungen 3 UO₂O · As₂O₃, 2 UO₂O · As₂O₃ und UO₂O · As₂O₃ in den pH-Bereichen 7,0–9,9 bzw. 6,0–7,5 bzw. 5,0–6,8. Der Anteil von Uranyl in den Alkaliarseniten wächst mit wachsender Konzentration von Na₂O. Die Bildung der Uranylarsenite ist also eine Funktion der H⁺-Ionenkonzentration. Wir fanden, daß die Ausfällung dieser Verbindungen fast quantitativ ist.

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The stoichiometry of the compounds formed by the interaction of uranyl nitrate and different alkali arsenites (ortho-, pyro-, and meta-) have been investigated by means of pH and conductometric titrations. The breaks and inflections in titration curves provide cogent evidence for the formation of 3 UO₂O · As₂O₃, 2 UO₂O · As₂O₃ and UO₂O · As₂O₃ in pH ranges 7.0–9.9, 6.0–7.5 and 5.0–6.8 respectively. The proportion of uranyl increases with the increase in the concentration of Na₂O molecules in alkali arsenites. The formation of uranyl arsenites is thus a function of H⁺ ion concentration. The precipitation of these compounds has been found to be almost quantitative.

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Mit 4 Abbildungen     

Studies on synthesis, characterization and thermochemistry of Mg2[B2O4(OH)2]·H2O

A new magnesium borate Mg₂[B₂O₄(OH)₂]·H₂O has been synthesized by the method of phase transformation of double salt at hydrothermal condition and characterized by XRD, IR, TG and DSC. The enthalpy of solution of Mg₂[B₂O₄(OH)₂]·H₂O in 0.9764 mol L^–1 HCl was determined. With the incorporation of the enthalpies of solution of H₃BO₃ in HCl (aq), of MgO in (HCl+H₃BO₃) (aq), and the standard molar enthalpies of formation of MgO(s), H₃BO₃(s), and H₂O(l), the standard molar enthalpy of formation of –(3185.78±1.91) kJ mol^–1 of Mg₂[B₂O₄(OH)₂]·H₂O was obtained.This revised version was published online in November 2005 with corrections to the Cover Date.     

Untersuchung von Eisen(III)-phosphiten im Hinblick auf die Wasserstoffbindungen

Iron(III) phosphites, vic. Fe₂(HPO₃)₃·9 H₂O, FeH₃P₂O₆·3 H₂O, FeH₆P₃O₉·H₂O and Fe₄H₃₃P₁₅O₄₅·6 H₂O were studied by means of powder X-ray, thermographic, IR and UV spectroscopy methods and by measurement of magnetic susceptibility. From the results obtained, and from analogy with phosphites studied earlier, the following structural model can be proposed: in the compounds studied, every iron atom is surrounded by six oxygen atoms of the water molecules and phosphite or, polyorthophosphite anions which form a weak ligand field of approximately octahedral symmetry. In Fe₂(HPO₃)₃·9 H₂O, symmetry of the anion is decreased from the point group C_3v to the C_s group. This anion is characterised by two bonding distances between phosphorus and oxygen atoms,r _PO=1,46 Å andr _{PO 2}=1,50 Å, the respective force constants beingK _PO=8.7 mdyn/Å andK _PO2=7.1 mdyn/Å. Three types of hydrogen bonds occur in the crystal lattices of the compounds studied. The weakest bond (bond lengthr=2.86–2.88 Å, bond energyE=4.6–5.0 kcal/bond) is formed between molecules of hydrate water, its energy approaching that of the hydrogen bond in liquid water. The stronger hydrogen bond (r=2.67–2.70 Å,E=5.7 to 8.0 kcal/bond) is found between water molecules and phosphite or polyorthophosphite anions. The strongest hydrogen bond (r=2.55–2.64 Å) is formed by polyorthophosphite anions, linking hydroxyl groups to oxygen atoms bound to different phosphorus atoms.     

Metal complexes of the diuretic drug furosemide

New complexes of the formulaeM(fur)₂·2H₂O (M = Mn, Cu, Zn),M(fur)₂·3H₂O (M = Co, Ni, Cd), Hg₂(fur)₃Cl₂·2H₂O, Pd(fur)Cl·H₂O and Rh(fur)₃·3H₂O, wherefurH = 4-chloro-N-(2-furfuryl)-5-sulfamoylanthranilic acid, have been prepared and characterized by conductivity measurements, X-ray powder patterns, thermal methods, effective magnetic moments as well as by IR, ligand field,¹H-NMR and ESR spectroscopic studies. The anionfur ^– shows a chelated bidentate O(carboxylato), N(imino)-coordinating behaviour.

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Metallkomplexe der diuretischen Droge Furosemid

Zusammenfassung Neue Komplexe der Verbindungen:M(fur)₂·2H₂O (M = Mn, Cu, Zn),M(fur)₂·3H₂O (M = Co, Ni, Cd), Hg₂(fur)₃Cl₂·2H₂O, Pd(fur)Cl·H₂O und Rh(fur)₃·3H₂O, wobeifurH 4-chlor-N-(2-furfuryl)-5-sulfamoylanthanilsäure ist, wurden dargestellt. Die Komplexe wurden durch Leitfähigkeitsmessungen, Röntgen-Pulver-Aufnahmen, thermogravimetrische Analysen, Messungen des effektiven magnetischen Dipolemomentes sowie durch spektroskopische Untersuchungen (IR,¹H-NMR und ESR) charakterisiert. Das Anionfur ^– zeigt das Verhalten einer Chelat-bidentat-O(carboxylato),N(imino)-Koordination.

     

An open-shell INDO study of models for the stabilized O− ion in γ-irradiated alkaline ices

Structural models for stabilized O^– in -irradiated alkaline ices are evaluated. INDO calculations on hydrated O^– indicate octahedral coordination and hydrogen bond orientations for the water molecules are preferred. INDO results for hydrated OH^– are compared with crystallographic data for NaOH hydrates: a scaling factor for calculated hydrogen bond lengths is developed and applied to hydrogen bonded O^– models. The hydrated O^– model is closely similar to the hydrated anions in KF · 4H₂O, NaOH · 4H₂O, and NaOH · 7H₂O. A second model is developed, involving H₃O⁺ along with H₂O, in the O^– stabilization shell. Both models are discussed in terms of alkaline ice radiation chemistry.     

Chromium(III) Hydroxide Solubility in The Aqueous Na+-OH?-H2PO?4-HPO2?4-PO3?4-H2O System: A Thermodynamic Model

Chromium(III)-phosphate reactions are expected to be important in managing high-level radioactive wastes stored in tanks at many DOE sites. Extensive studies on the solubility of amorphous Cr(III) solids in a wide range of pH (2.8–14) and phosphate concentrations (10^–4 to 1.0 m) at room temperature (22±2)°C were carried out to obtain reliable thermodynamic data for important Cr(III)-phosphate reactions. A combination of techniques (XRD, XANES, EXAFS, Raman spectroscopy, total chemical composition, and thermodynamic analyses of solubility data) was used to characterize solid and aqueous species. Contrary to the data recently reported in the literature,⁽¹⁾ only a limited number of aqueous species [Cr(OH)₃H₂PO^–₄, Cr(OH)₃(H₂PO₄)^2–₂), and Cr(OH)₃HPO^2–₄] with up to about four orders of magnitude lower values for the formation constants of these species are required to explain Cr(III)-phosphate reactions in a wide range of pH and phosphate concentrations. The log K^o values of reactions involving these species [Cr(OH)₃(aq)+H₂PO^–₄⇌Cr(OH)₃H₂PO^–₄; Cr(OH)₃(aq)+2H₂PO^–₄⇌Cr(OH)₃(H₂PO₄)^2–₂; Cr(OH)₃(aq)+HPO^2–₄⇌Cr(OH)₃HPO^2–₄] were found to be 2.78±0.3, 3.48±0.3, and 1.97±0.3, respectively.     

Sulfito- und Thiosulfato-Komplexe des Kobalts(III) mitα-Benzildioxim Überα-Dioximinkomplexe der Übergangsmetalle, 52. Mitt.

Some new ligand exchange reactions of [Co(diph·H)₂Cl(H₂O)] and [Co(diph·H)₂(SO₃)(H₂O)]^– complexes with N₃ ^–, S₂O₃ ^2– and with aromatic and heterocyclic amines were carried out. A series of derivatives of the types [Co(diph·H)₂(SO₃)X] ^n– (X=N₃ ^–, S₂O₃ ^2– oramine) and [Co(diph·H)₂(S₂O₃)₂]^3– were described and characterized. Some structural problems are resolved and discussed on the basis of UV and IR spectral data.     

Crystal Structure and Properties of Rb4H2I2O10 · 4H2O

Single crystals of the Rb₄H₂I₂O₁₀· 4H₂O were synthesized for the first time and studied by X-ray diffraction analysis. The crystals are monoclinic, a = 7.321(6) Å, b = 12.599(8) Å, c = 8.198(8) Å, = 96.30(7)°, Z = 2, space group P2₁/c. The H₂I₂O₁₀ ^4– anion is formed by the edge-sharing IO₆ octahedra. The anions are united by hydrogen bonds into a chain running along the x axis. The chains are combined by water molecules into a three-dimensional structure through hydrogen bonds. The compound is a proton conductor. The conductivity values measured at 20–60°C vary within 10^–6 to 10^–4 ohm^–1 cm^–1.     

UR-spektroskopische Untersuchungen an zeolithischen Heptagermanaten

Zusammenfassung Der direkte Nachweis von H₃O⁺-Ionen bzw. OH^–-Ionen in zeolithischen Germanaten wird durch UR-spektroskopische Untersuchungen erbracht. Hydronium-Ionen liegen vor beiM(I)₃HGe₇O₁₆·nH₂O sowie bei Ba- und Pb-Zeolithen der FormM(II)_2–x H_2x Ge₇O₁₆·nH₂O, während man in Ba- und Pb-Zeolithen der ZusammensetzungM(II)_2+x Ge₇O₁₆(OH)_2x ·nH₂O Hydroxyl-Ionen beobachtet.

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By IR-spectroscopic investigations of zeolitic germanates of formulaM(I)₃HGe₇O₁₆·nH₂O as well as of Ba- and Pb-zeolites of formulaM(II)_2–x H_2x Ge₇O₁₆·nH₂O the presence of H₃O⁺-ions can be detected. On the other hand inM(II)_2+x Ge₇O₁₆(OH)_2x ·nH₂O (M=Ba, Pb) hydroxyl ions are observed.

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Mit 2 Abbildungen     

Crystal structure refinement of basic tellurium nitrate: A reformulation as (Te2O4H)+(NO3)−

Basic tellurium nitrate crystallizes in the space group Pnma witha=14.607 (1),b=8.801 (1), andc=4.4633 (4) Å. Full-matrix least-squares refinement of automatic diffractometer data converged to a residualR=0.036 (R _w =0.046) for 899 independent reflections. A detailed analysis of the structural data leads us to reformulate this compound as (Te₂O₄H)⁺(NO₃)^– with a basic structural element consisting of a charged two-dimensional puckered Te₂O₄H⁺ network with discrete NO₃ ^– anions, an example of apositively-charged network structure.

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Verfeinerung der Kristallstruktur von basischem Telluriumnitrat. Eine Umformulierung in (Te₂O₄H)⁺(NO₃)^–

Zusammenfassung Basisches Telluriumnitrat kristallisiert in der Raumgruppe Pnma mita=14,607 (1),b=8,801 (1) undc=4,4633 (4) Å. Die verfeinernde Auswertung der Diffraktometerdaten konvergierte zuR=0,036 (R _w =0.046) für 899 unabhängige Reflexe. Eine detaillierte Analyse der Strukturdaten führte zu einer Umformulierung dieser Verbindung als (Te₂O₄H)⁺(NO₃)^–, wobei die Basisstruktur aus einem geladenen, zweidimensionalen, gefalteten Te₂O₄H⁺ Netzwerk mit getrennten NO₃ ^– Anionen besteht. Es stellt dies ein Beispiel einerpositiv geladenen Netzstruktur dar.

     

Cubic structure II double clathrate hydrates with tetra(n-propyl)ammonium fluoride

A double clathrate hydrate with the composition THF·0.5(n-Pr)₄NF·16H₂O and cubic structure II (CS-II,a=17.67 Å) has been obtained. Its experimental density is 1.053±0.001 g/cm³; its melting point is 8.1°C, i.e. 3.1°C higher than that of the THF·17H₂O hydrate. The double hydrates of acetone, 1,4-dioxan, trimethyleneoxide and 1,3-dioxolane with (n-Pr)₄NF have melting points of –14.8, –5.5, –2.6 and –9.6°C, respectively. With pressure increase up to 6 kbar the melting points of the double hydrates increase monotonously in contrast to common CS-II hydrates. The friability of the structure of the hydrates (the packing coefficient) and their sensitivity to pressure (dT/dP) are compared.The results of this work have been reported at the International Seminar on Inclusion Compounds, Jaszowiec (Poland), 24–26th September 1987.