Ligand exchange between bis-acetylacetonato cobalt(II) and organotin compounds SnR2Cl2 (R=Ph, Et), II. Mechanism of ligand exchange between acetylacetonate complexes of Co(II)

Ligand exchange between the compounds Co(AA)₂Py₂ and Co(AA)Clpy_x (x=1 or 3) formed in the, system, CO(AA)₂–SnR₂Cl₂(R=Ph, Et) in chloroform with pyridine has been established to be catalyzed by SnR₂Cl₂. An interpretation of the catalytic action of SnR₂Cl₂ is suggested.

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, Co(AA₂py₂ Co(AA)Clpy_x (x=1 3) (Co(AA)₂–SnR₂Cl₂ (R=Ph, Et) , SnR₂Cl₂. SnR₂Cl₂.

     

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.     

Triterpene Glycosides of Astragalus and Their Genins. LXI. Occurrence of Cycloartane 6-O-Monodesmosides

Cyclosiversigenin 6-O--L-rhamnopyranoside and 6-O--D-glucopyranoside were isolated fromAstragalus coluteocarpusBoiss. (Leguminosae) andAstragalus dissectusB. Fedtsch. et N. Ivanova, respectively. Cyclosiversigenin 5-O--L-rhamnopyranoside was shown to be an artifact forAstragalus coluteocarpus.Thus, the cyclosiversigenin 6-O--D-glucopyranoside that was isolated from certainAstragalusspecies is hypothesized also to be an artifact. Glycosylation of the 6 -hydroxyl group of cycloartanes by D-glucose and D-xylose, in contrast with other substituents, does not change the low-field position of the PMR signal of the 4-CH ₃ group (1.65 2.01 ppm) that is caused by the influence of deuteropyridine directly on the 6 -hydroxyl. Obviously one of the hydroxyls of the -D-glucopyranoside or -D-xylopyranoside residues has the same effect in this instance.     

Bauxites as hydrotreatment catalysts

The effects of calcination temperature on structural and textural characteristics of two Greek bauxites were examined by different physicochemical techniques. Although the above minerals exhibited lower activity than a commercial CoMo/Al₂O₃ catalyst, they were evaluated as possible hydrotreating catalysts.

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. , CoMo/Al₂O₃, , .

     

Crystal structure of the synthetic analog of radtkeite Hg<Subscript>3</Subscript>S<Subscript>2</Subscript>Cl<Subscript>1.00</Subscript>I<Subscript>1.00</Subscript>

The results of structural studies of the synthetic analog of the radtkeite mineral Hg₃S₂Cl_1.00I_1.00 are analyzed. The crystal structure of the compound has been refined; the unit cell parameters are a _m = 16.827(4) , b _m = 9.117(1) , c _m = 13.165(5) , = 130.17(2)°, V = 1543.3(8) ³, space group C2/m, Z = 8, R = 0.0527. A possible transition a ₀ = a _m; b ₀ = a _m + 2c _m; c ₀ = –b _m to the pseudo-orthorhombic F cell previously determined for radtkeite, where one of the angles ( ₀ ) is slightly different from 90° (89.55°), has been found. Each sulfur atom in the structure is bonded to three mercury atoms, forming SHg₃ umbrellas with distances 2.240(6) –2.474(8) and angles HgSHg 94.7(2)°–102.9(2)°. The SHg₃ fragments are linked through Hg vertices to form corrugated [Hg₁₂S₈] layers. The halogen atoms lie inside and between the [Hg₁₂S₈] layers; the distances are Hg-Cl and Hg-I 2.783(7) , 2.961(7) , and 3.083(4) –3.311(3) , respectively.Original Russian Text Copyright © 2004 by N. V. Pervukhina, S. V. Borisov, S. A. Magarill, D. Yu. Naumov, V. I. Vasiliev, and B. G. NenashevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 755–758, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Crystal and Molecular Structure of 1-( p -Tolyl)-4-[4-(N-naphthalimido)butyl]piperazine

An X-ray structure analysis of 1-(p-tolyl)-4-[4-(N-naphthalimido)butyl]piperazine (I) was carried out: a=9.551(3), b=13.775(3), á=8.917(4) , =103.96(3), =101.47(4), =92.60(3)°, V=1110.4(7) ³, Z=2,_calc=1.279 g/cm³, =0.644 mm, space group P 1, 4239 nonzero reflections, R=0.056. The molecule is linear elongated. The p-tolyl and naphthalimide fragments are almost planar, while the piperazine cycle has a chair conformation. The long well-packed molecules form parallel and antiparallel chains with van der Waals interactions between them.     

Etude du systeme binaire selenium-tellure

Integral heats of mixing have been measured at 738 K by drop calorimetry. Liquidus and solidus temperaturesT ₉ and recrystallisation temperatures have been measured by thermal analysis.

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Zusammenfassung Integrale Mischungswärmen wurden bei 738 K kalorimetrisch gemessen. Liquidus-, Solidus- and Rekristallisationstemperaturen sowieT ₉ wurden thermoanalytisch bestimmt.

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738 . , _g .

     

Effects of radioactivity on surfaces: I. Influence of Cr-51 on the catalytic activity of chromium catalysts

Chromium catalysts were prepared on monolith supports, some of them with radioactive Cr-51 in the surface. The dehydrogenation-hydrogenation reaction of cyclohexene was used to compare the catalytic activities of the radioactive and inactive catalysts. Differences were observed in the distribution of the main products at low temperatures and of the byproducts also at high temperatures.

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, Cr-51. - . , — , .

     

IR and thermal studies on lithium oxomolybdenum(VI) oxalate

A new molybdenum(VI) complex, Li₂[Mo₂O₆(C₂O₄)] · 2 H₂O (LMO), was prepared and characterized by chemical analysis and IR spectral studies. Its thermal decomposition was studied by using TG and DTA techniques. LMO loses its two moles of water between 75 and 170° to give the anhydrous product, which decomposes in three stages between 240 and 380°. The first two stages occur in the temperature ranges 240–280° and 280–305°, to give intermediates with the tentative compositions Li₆[Mo₆O₁₉(C₂O₄)₂] and Li₆[Mo₆O₂₀(C₂O₄)], respectively. In the third stage, which extends up to 380°, Li₆[Mo₆O₂₀(C₂O₄)] decomposes to give the end-product, Li₂Mo₂O₇.

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Zusammenfassung Ein neuer Molybdän(VI)-Komplex der Formel Li₂[Mo₂O₆(C₂O₄)] · 2 H₂O (LMO) wurde dargestellt und durch chemische Analyse und IR-spektroskopisch charakterisiert. Die thermische Zersetzung dieses Komplexes wurde mittels TG und DTA untersucht. LMO verliert die zwei Wassermoleküle zwischen 75 und 170° unter Bildung des wasserfreien Produktes, das zwischen 240 und 380° in drei Stufen zersetzt wird. Die in den Temperaturbereich von 240–280° und 280–305° verlaufenden ersten zwei Reaktionsschritte ergeben Intermediäre der tentativen Zusammensetzung Li₆[Mo₆O₁₉(C₂O₄)₂] bzw. Li₆[Mo₆O₂₀(C₂O₄)]. In dem sich bis 380° erstreckenden dritten Reaktionsschritt wird Li₆[Mo₆O₂₀(C₂O₄)] unter Bildung des Endproduktes Li₂Mo₂O₇ zersetzt.

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Li₂[MO₂O₆(C₂O₄] · 2 ₂ . . - 70–170° , , 240–380°. 240–280° 280–305° - Li₆[Mo₆O₁₉(C₂O₄)₂] Li₆[Mo₆O₂₀(C₂O₄)]. - 380° Li₂Mo₂O₇.

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The authors are grateful to Prof. S. N. Tandon, Head of the Chemistry Department, for providing the research facilities.     

Komplexe des Nickels mit p-Methylbenzamidoxim

Zusammenfassung Die Komplexbildung des p-Methylbenzamidoxims (pMB) mit Ni²⁺ wurde in neutraler und alkalischer Lösung spektrophotometrisch untersucht. In neutraler Lösung wird ein grüner Komplex 11 gebildet, dessen Bildungskonstante ₁=1,12 ist. In alkalischer Lösung werden zwei Komplexe (11 und 12) gebildet mit Bildungskonstanten ₁=4·10⁵ und ₂=0,2.

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Nickel complexes with p-methyl benzamide oxime

The complex formation of p-methyl benzamidoxime with Ni²⁺ was studied spectrophotometrically in neutral and in alkaline solution. A green complex 11 is formed in neutral solution. Its formation constant is ₁=1.12. In alkaline solution two complexes (11 and 12) are formed. Their formation constants are ₁=4·10⁵ and ₂=0,2 resp.

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Mit 6 Abbildungen     

The chemistry of uranium

The thermal decomposition reactions of various hexanitrato uranium(IV) species, M₂U(NO₃)₆ where M=Cs⁺, NEt ₄ ⁺ , AsPh ₄ ⁺ and PPh ₄ ⁺ have been studied.The overall decomposition reaction can be described in terms of an oxidation-reduction reaction in which the nitrate oxidizes the uranium. The enthalpies of decomposition were found to be very similar, approximately 55 kJ mole^–1 except for the PPh ₄ ⁺ -salt which was only 27 kJ mole^–1.The decomposition kinetics of all the compounds were studied and found to be complex — especially during the initial stages of the reaction.

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Zusammenfassung Die thermischen Zersetzungsreaktionen verschiedener Hexanitratouran (IV)-Arten der Formel M₂U(NO₃)₆ (M=Cs⁺, NEt ₄ ⁺ , AsPh ₄ ⁺ und PPh ₄ ⁺ ) wurden untersucht.Die allgemeine Zersetzungsreaktion kann durch eine Oxidations-Reduktionsreaktion beschrieben werden, in der Uran durch Nitrat oxidiert wird. Die Zersetzungsenthalpien erwiesen sich als sehr ähnlich, annähernd 55 kJ. mol^–1 mit Ausnahme des PPh ₄ ⁺ -Salzes, dessen Wert nur 27 kJ. mol^–1 betrug.Die Zersetzungskinetik sämtlicher Verbindungen wurde studiert und für komplex gefunden, besonders in den Anfangsstadien der Reaktion.

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Résumé On a étudié la décomposition thermique des diverses espèces d'hexanitrate d'uranium IV de formule: M₂U(NO₃)₆ (M=Cs⁺, NEt ₄ ⁺ , AsPh ₄ ⁺ et PPh ₄ ⁺ ).La réaction générale de la décomposition peut être décrite par une réaction d'oxydo-réduction, dans laquelle le nitrate oxyde l'uranium. On a trouvé que les enthalpies de décomposition étaient très similaires, environ 55 kJ. mole^–1, à l'exception du se! de PPh ₄ ⁺ dont la valeur n'était que 27 kJ. mole^–1.On a étudié la cinétique de décomposition de tous les composés. Elle est complexe, spécialement pendant les étapes initiales de la réaction.

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oypaa(IV) M₂U(NO₃)₆, M=Cs⁺, Et₄N⁺, Ph₄As⁺ Ph₄P⁺. - , . , 55 .^–1, Ph₄P⁺ — , 27 .^–1. , .

     

Kinetics of Cu(II)-ion catalyzed oxacillin hydrolysis

The kinetics of Cu(II)-ion catalyzed oxacillin hydrolysis have been studied. The applicability of a reaction scheme is tested together with the influence of several factors and the kinetic and thermodynamic parameters of the reaction are determined.

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CO₂ TiO₂ , . CO₂ O ₃ ^– O ₂ ^– . H₂O₂/TiO₂, 150–200°C, CO₂–O ₂ ^– .

     

Preparation and characterization of Ru?Pb supported catalysts

Decomposition of Mn₃Mo₂TeO₁₂ during oxidation of toluene to benzaldehyde was observed. Depending on the surface composition of the initial catalyst, the decomposition leads to less active but highly selective MnMoTeO₆ or to MnMoO₄ which is not selective in toluene oxidation.

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Mn₃Mo₂TeO₁₂ . , MnMoTeO₆, MnMoO₆.

     

The catalytic system [(Cp2TiCl)2]:LiAlH4 in aromatic solvents,Part II. Formation of η3-allyltitanocene derivatives in the presence of dienes — their structure and e.s.r. spectra

Summary The addition of dienes to the system [(Cp₂TiCl)₂] LiAlH₄toluene changes the system so that the complex [Cp₂TiAlH₄] is quantitatively formed instead of a titanocene hydride — aluminium hydride cluster. The complex [Cp₂TiAlH₄] is further converted into ³-allyltitanocene derivatives ([Cp₂TiA]) if the diene structure is suitable for formation of stable [Cp₂TiA] compounds and if the equilibrium [Cp₂TiAlH₄]+diene[Cp₂TiA]+A1H₃ is shifted towards the formation of [Cp₂TiA] by the excess of diene. All the compounds [Cp₂TiA] exhibit high-resolution e.s.r. spectra at g=1.993, showing interaction of the unpaired electron with the cyclopentadienyl and ³-allyl protons. The e.s.r. spectra clearly reveal the presence of alkyl substituents atsyn-1,3-positions of ³-allyl ligand, and show a triplet of multiplets for (³-allyl)titanocene, doublets of multiplets for (1-alkyl-³-allyl)titanocenes and single multiplets for (1,3-dialkyl-³-allyl)-titanocenes. thermal isomerization of (1,3-dimethyl-³-allyl)-titanocene and (1-methyl-3-ethyl-³-allyl)titanocene, hitherto considered as the stable Cp₂TiA compounds, into (1-alkyl-³-allyl)titanocenes was confirmed by e.s.r. and electronic absorption spectroscopy as well as by chemical means.     

Oxidative coupling of 5-membered heterocycles catalyzed by a Pd(II)-heteropolyacid system in dimethylformamide

Oxidative coupling of thiophene and 2-methylfuran to the corresponding dihetaryls in DMFA medium occurs in the presence of the homogeneous catalytic system Pd(II)-molybdovanodophosphoric heteropolyacid (HPA). The data obtained show that HPA may act as a reversible oxidant in polar aprotic media.

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, Pd(II)- 2- . , .

     

Crystal and molecular structure of trans-diiodobis-(1-methyl-5-nitroimidazole)platinum(II)

Summary A new platinum complex of 1-methyl-5-nitroimidazole has been obtained and characterized by elemental analysis, i.r. and n.m.r. spectroscopy. The structure of [PtI₂-(C₄ H₅N₃O₂)₂] has been determined by single-crystal X-ray diffraction. The crystals are triclinic: P1, a = 15.640(3), b = 12.617(2), c = 6.701(1) , = 102.77(5), = 101.15(5), = 100.71(5)°, V = 1228.6(3) ³, Z = 3, D_x = 2.851(6) Mg m^–3, (MoK ) = 0.71069 , = 12.85 mm^–, F(000) = 948, final R = 0.038 for 2859 reflections. The complex consists of monomeric PtI₂(1-methyl-5-nitroimidazole)₂ units. The coordination geometry is square-planar. The two 1-methyl-5-nitroimidazole ligands are trans coordinated to platinum.     

Phase equilibria and oxidation mechanisms in the LA-S-O system

The phase diagram of the La-S-O system at 1073 K was established with the vacuum seal technique. Six phases exist at this temperature: La₂O₃ (B-type), LaS₂, La₂S₃, La₂O₂SO₄, La₂O₂S and La₂O₂S₂. The thermodynamic functions for the reaction La₂O₂SO₄=La₂O₃+SO₂+1/2 O₂ were determined by using the emf method at temperatures from 1123 to 1373 K. The mechanisms of the oxidation reactions in the La-S-O system under different partial pressures of oxygen (–4.4 < log <–0.7) were also investigated by means of DTA, TG and powder X-ray diffractometry.

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Zusammenfassung Das Phasendiagramm des La-S-O-Systems bei 1073 K wurde bestimmt. Bei dieser Temperatur liegen 6 Phasen vor, und zwar La₂O₃ (B-Typ), LaS₂, La₂S₃, La₂O₂SO₄, La₂O₂S und La₂O₂S₂. Für die Reaktion La₂O₂SO₄=La₂O₃+SO₂+1/2 O₂ wurden die thermodynamischen Funktionen im Temperaturbereich von 1123–1373 K nach der EMF-Methode bestimmt. DTA, TG und Pulver-Röntgendiffraktometrie wurden zur Untersuchung der Mechanismen der im La-S-O-System verlaufenden Oxydationsreaktionen herangezogen, wobei der Sauerstoffpartialdruck in den Grenzen von – 4.4 < log < <-0.7 variiert wurde.

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La-S-O 1073 . : La₂O₃ (-), LaS₂, La₂S₃, La₂O₂SO₄, La₂O₂S La₂O₂S₂. . . ., La₂O₂SO₄=La₂O₃+ SO₂+1/2 ₂ 1123–1373. , La-S-O –4.4 < log < –0.7.

     

Kinetics of Cr(VI) and V(V) oxidation of trans-stilbene and indene

Title reactions are acid catalyzed and strongly dependent on the permittivity of the medium. With Cr(VI) indene reacts faster than trans-stilbene, but with V(V), trans-stilbene reacts faster than indene. The mechanism is discussed.

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. Cr(VI) , -, V(V) - , . , .

     

Identification of exchange-coupled V4+ and Cu2+ ions in Cu?V?Mo oxide systems

ESR studies of X(CuO)·V₂O₅·8.3 MoO₃ (X=1–2) calcined in flowing nitrogen at 250–350 °C have revealed the exchange interaction of Cu²⁺ and V⁴⁺ ions that form a paramagnetic system.

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X(CuO) V₂O₅·8,3 MoO₃, X=1–2, , 250–350°C, Cu²⁺ V⁴⁺, .

     

Kinetics and mechanism of oxidation of D-altrose by aqua-cerium(IV) in perchloric acid medium

Kinetics of the oxidation of D-altrose by Ce(IV) perchlorate has been studied in perchloric acid medium. At equivalent concentrations the overall order of the reaction is two, being unity in each reactant. The reaction is characterized by a primary positive kinetic salt effect. Perchloric acid has been found to enhance the rate, while the addition of the reaction products retards the rate. No evidence for initial complexation has been obtained. Thermodynamic parameters have been determined and a mechanism consistent with the observed results is proposed.

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D- Ce(IV) . , . . , . . , .