Synthesis and X-Ray Crystal Structure Study of ]2-Methyl-4-(2-methylbenzoyl)-phenoxy] Acetic Acid Hydrazide

Benzophenone analog 3 has been synthesized and characterized by the X-ray diffraction (XRD) method. The compound crystallizes in a monoclinic space group P2₁/c with cell parameters a = 7.701(8) Å, b = 7.151(5) Å, c= 28.323(3) Å, = 104.639(4)°, Z = 4. The structure exhibits intra- and intermolecular hydrogen bonding of the type N–HO, C–HO, and N–HN. The molecules are interlinked through hydrogen bonds forming an infinite chain. This polymeric-like structure may play an important role in biological activity.     

Reaction of H2PtCl6 with 18-crown-6 and dibenzo-18-crown-6 in 1,2-dichloroethane and acetonitrile

Compounds of the compositions [2(18-crown-6)6(H₂O)2(C₂H₄Cl₂){Pt²⁺(C₂H₄)}(Pt₂Cl₁₀)^2–], [4(18-crown-6)2(OH₃)⁺2(OH₂)2(NH₃)(Pt₂Cl₁₀)^2–], [(dibenzo-18-crown-6)6(H₂O){Pt²⁺(C₂H₄)}(Pt₂Cl₁₀)^2–], and [4(dibenzo-18-crown-6)2(OH₃)⁺2(OH₂)2(NH₃)Pt₂Cl₁₀)^2–] were prepared by reactions of H₂PtCl₆ with 18-crown-6 and dibenzo-18-crown-6.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1593–1599.Original Russian Text Copyright © 2004 by Guseva, Busygina, Khasanshin, Polovnyak, Yarkova, Yusupov.This revised version was published online in April 2005 with a corrected cover date.     

Gold(I) Formamidinate Clusters: The Structure, Luminescence, and Electrochemistry of the Tetranuclear, Base-Free [Au4(ArNC(H)NAr)4]

The structures of the tetragold(I) formamidinate cluster complexes, [Au₄(ArNC(H)NAr)₄], Ar=C₆H₄-4-OMe (1), C₆H₃-3,5-Cl (2), C₆H₄-4-Me (3), have been characterized by x-ray crystallography. The range of AuAu distances is 2.8–3.0 Å. The angles at AuAuAu are acute and obtuse 70 and 109°, 88 and 91°, and 63 and 116° in 1, 2, and 3, respectively. The four gold atoms are located at the corner of a rhomboid with the formamidinate ligands bridged above and below the near plane of the four Au(I) atoms. The tetranuclear gold(I) complexes show a bright blue-green luminescence under UV light, with an emission at 490 nm and a weak emission at 530 nm in the solid state, at room temp and 77 K. The oxidation of the formamidinate cluster, 1, has been studied electrochemically in 0.1 M Bu₄NPF₆/CH₂Cl₂ at a Pt working electrode with different scan rates. Three waves were obtained, 0.75, 0.95, and 1.09V vs. Ag/AgCl at a scan rate of 500 mV/s, the three waves are reversible. The potentials are independent of the scan rate in the range 50 mV/s to 3 V/s. The current at the third wave is larger than those at the first two.     

An Inorganic-Organic Hybrid Supramolecular Hydrogen-Bonding and π-π Stacking Network Containing Ge4S4− 10 Cluster: Synthesis and Characterization of (H2bipy)2Ge4S10⋅(bipy)⋅7H2O (bipy=4,4′-bipy)

The reactions of TMA₄Ge₄S₁₀ (TMA=tetramethylammonium), Cu(NO₃)₂3H₂Oand 4,4-bipy under hydrothermal environment result in the formation of (H₂bipy)₂Ge₄S₁₀(bipy)7H₂O (1), which has been structurally characterized by single crystal X-ray analysis. The 3-D structure of 1 can be viewed as an inorganic-organic hybrid supramolecular hydrogen-bonding (hydrogen bonds: O–HO, N–HN, C–HO, N–HO, and O–HS) and - stacking network containing Ge₄S^4– ₁₀ clusters and novel [H₂bipybipyH₂bipy] trimers.     

Study of acid-base interactions of mono- and diazaporphyrin indium complexes with acetic and trifluoroacetic acids by <Superscript>1</Superscript>H NMR and electronic spectroscopy

Indium complex of 13,17-dibutyl-2,3,7,8,12,18-hexamethyl-5-azaporphyrin (Cl)InMAP was synthesized, and acid-base interactions of the meso-nitrogen atoms in (Cl)InMAP and its diaza analog (Cl)InDAP with acetic and trifluoroacetic acids were studied by ¹H NMR and electronic spectroscopy. Depending on the medium, the complexes and proton-donor species HA give rise to acid solvates >N(HA)_n which are converted to final acid-base interaction products, H-complexes >NH+A^–(HA)_m or ionic associates >NH⁺A^–(HA)_l , as the acidity of the medium rises. In acetic acid solution, the acid solvates derived from more basic (Cl)InMAP exist in equilibrium with the H-associates (pK _a1 = 4.45±0.03). From (Cl)InDAP, the corresponding H-associates are formed only in the presence of H₂SO₄ (pK _a1 = 2.10±0.03). In more polar media (solutions of trifluoroacetic acid in methylene chloride), ionic associates are formed, which involve one [(Cl)InMAP, pK ₁ = 2.46±0.02] or two meso-nitrogen atoms [(Cl)InDAP, pK ₁ = 2.11±0.03, pK ₂ = 0.41±0.04).Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1546–1556.Original Russian Text Copyright © 2004 by Stuzhin, Ivanova, Migalova.This revised version was published online in April 2005 with a corrected cover date.     

Crystal Structure of [Co?6H2O][Co?4H2O?2Gly]?2SO4

The crystals of [Co6H₂O][Co4H₂O2Gly]2SO₄ were studied by X-ray diffraction analysis (triclinic, P , a = 5.975(5), b = 15.469(5), c = 6.765(5) , =120.71(5), =83.23(5), =98.77(5)°). The structure contains complex cations of two types: [Co6H₂O]²⁺ and [Co4H₂O2Gly]²⁺ and SO ₄ ^2– anions linked by hydrogen bonds and electrostatic forces. Three chemically nonequivalent charged layers can be distinguished in the structure: one layer is formed by cobalt hexaaqua complexes, another by [Co4H₂O2Gly]^2– complexes, and the third layer consists of sulfate anions interlaying the former two. The layers alternate along the b axis and are connected by a 3D system of hydrogen bonds.     

Redox reactions of disulfiram: a pulse-radiolysis study

Redox reactions of disulfiram (DSF) were studied in aqueous solutions using the pulse-radiolysis technique. Reactions of DSF with one-electron oxidants Br₂ ^- and N₃, generated pulse radiolytically in aqueous solution at pH 7, yielded a transient (_max = 480 nm) which exhibited the characteristics of a disulphide cation radical and decayed by second-order kinetics. Reactions of DSF with halogenated peroxyl radicals CCl₃O₂, CHCl₂O₂, CH₂ClO₂ and CBr₃O₂ led to the formation of an adduct absorbing at 580 nm. The reduction potential was estimated to be 1.24 ± 0.06 V vs. NHE.     

Molecular Encapsulation of Half-Sandwich Complexes of Iron with Cyclodextrins: New Laminar Materials

The treatment of - and -cyclodextrins with the half-sandwich complexes of iron afford the inclusion compounds CpFe(L₂)XCD ( and ) (X = Cl, I; L = CO; L₂ = dppe, dppe = (Ph)₂P(CH₂)₂P(Ph)₂), [CpFe(L₂)L-]PF₆CD ( and ) L- neutral donor ligands and[(Cp(dppe)Fe)₂-µ-CN]PF₆2CD ( and ). The inclusion compounds [Cp(dppe)Fe-NCCH₃]PF₆-CD and [Cp(dppe)Fe-(¹-dppm)]PF₆-CD have a laminar structure. The - and -cyclodextrin encapsulation effect on the electro-oxidation of the binuclear complex was studied using cyclic voltammetry.The electron-transfer reactions associated with the oxidation of the two different N-bonded and C-bonded organometallic fragments are substantially affected by and encapsulation.     

Gold(I) Pyrazolate Clusters: The Structure and Luminescence of the Tetranuclear, Base-Stabilized [(dppm)2Au4(3,5-Ph2Pz)2](NO3)2 ⋅ H2O

The tetranuclear Au(I) pyrazolate complex, [(dppm)₂Au₄(3,5-Ph₂Pz)₂](NO₃)₂  H₂O, 1, has been synthesized and structurally characterized. It is the first tetranuclear pyrazolate of Au(I) to have been found, although the trinuclear pyrazolates of Au(I) are well known. Complex 1 exhibits luminescence at 77 K when excited at 333 nm with an emission maximum at 454 nm. The emission has been assigned to ligand to metal charge transfer, LMCT, based upon the vibronic structure that is observed. The complex crystallizes in the monoclinic space group P2₁/c, with a=19.33(3) Å, b=20.26(3) Å, c=19.80(3) Å, =106.74(2)°, V=7425(17) ų, Z=8, and R=0.058. The Au    Au distances are Au(1)    Au(4)=3.185(3) Å, Au(1)    Au(2)=3.230(3) Å, Au(2)    Au(3)=3.079(3) Å, and Au(3)    Au(4)=3.280(3) Å.     

Mechanisms of Heterogeneous Processes in the System SiO2 + CH4: III. Products of >Si

Permenov  D. G.  Radzig  V. A. 《Kinetics and Catalysis》2004,45(2):273-278

2-[3-Phenyl-5-(m-Chlorophenyl)-2-Pyrazolin-1-yl]-3-Methyl-4(3H)-Quinazolinone

There are two molecules in the asymmetric unit (I and II). The structure consists of a 2-pyrazoline ring and three aromatic rings two of which are free and the third one is condensed with a 3-methyl-4(3H)-pyrimidine ring (4(3H)-Quinazolinone). While the pyrazoline ring is in the distorted envelope conformation, the free aromatic rings are planar and the pyrimidine ring deviates from the planarity. The crystal structure is stabilized by C–HO inter and intramolecular bonds.     

Possibilities of applying the Piloyan method of determination of decomposition activation energies in the differential thermal analysis of polynitroaromatic compounds and their derivatives

The Piloyan activation energiesE, as well as the initial exotherm temperaturesT _D, are determined for sixN-monoalkyl- and fiveN,N-dialkyl-2,4,6-trinitroanilines. By comparison withR _f-factors, orR _M-functions of paper chromatography, the molecular-structural dependences ofE andT _D are studied for these compounds. Relationships are also found between the termE · T _D ^–1 and theR _M-functions. The effects are discussed of the introduction of the 6-nitro group into the TV-substituted 2,4-dinitroanilines, and of the introduction of the 4-nitro group into the 2,6-dinitro analogues, upon the thermal stabilities of the resulting 2,4,6-trinitroanilines.

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Zusammenfassung Die AktivierungsenergienE nach Piloyan und die Anfangswerte der ExothermenT _D der sechsN-monoalkyl- und fünfN,N-Dialkyl-2,4,6-trinitroaniline wurden bestimmt. Unter Berücksichtigung des Vergleichs mitR _f-Faktoren oderR _M-Funktionen der Papierchromatographie wurden die molekularstrukturellen AbhÄngigkeiten der WerteE undT _D dieser Verbindungen untersucht. ZusammenhÄnge wurden auch zwischen dem AusdruckE · Tw _D ^–1 und denR _M-Funktionen gefunden. Der Einfluss der Einführung der 6-Nitrogruppe in dieN-substituierten 2,4-Dinitroaniline, sowie der Einfluss der Einführung der 4-Nitrogruppe in 2,6-Nitroanaloge auf die ThermostabilitÄt der resultierenden 2,4,6-Trinitroaniline werden erörtert.

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Résumé On a déterminé les énergies d'activation par la méthode de Piloyan ainsi que les températures initialesT _D de l'effet exothermique de sixN-monoalcoyl- et cinqN,N-dialcoyl-2,4,6-trinitroanilines. En se référant aux facteursR _F ou aux valeurs des fonctionsR _M en Chromatographie sur papier, on a étudié la dépendance entre les valeurs deE et deT _D sur les caractéristiques moléculaires-structurales de ces composés.On a également trouvé des rapports entre le termeE · T _D ^–1 et les fonctionsR _M. On discute l'influence de l'introduction du groupe 6-nitro dans les 2,4-dinitroanilinesN-substituées ainsi que l'influence de l'introduction du groupe 4-nitro dans les 2,6-dinitro analogues sur la stabilité thermique des 2,4,6-trinitroanilines qui en résultent.

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N-- N,N--2,4,6- E , T _D. R _f,- R _M — , - E T _D. E.T _D ^–1 R _M-. 6N- 2,4- 4 2,6- 2,4,6- .

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The authors would like to thank Mrs. Anna Colláková for careful DTA measurements, and Dr. Ladislav Smolka for help in the treatment of the measured results with the Wang 600 computer.     

Mechanisms of Reactions of H2O and NH3 Molecules with (≡Si–O)3Si⋅and (≡ Si–O)3Si–⋅ Radicals on the Silica Surface

Spin traps, which are diamagnetic centers (SiO)₂Si, are used to register low-molecular radicals OH, NH₂, and H formed by the reactions of H₂O and NH₃ molecules with the radicals (Si–O)₃Si and (Si–O)₃Si–O stabilized on the silica surface. The experimental data and the results of quantum-chemical calculations for model systems are used to determine the mechanism and thermochemical characteristics of these reactions. A new paramagnetic center (Si–O)₂SiNH₂ was identified on the silica surface, and its radiospectroscopic characteristics are determined.     

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.     

Laser-spectroscopic laboratory studies of atmospheric aqueous phase free radical chemistry

Nitrate radical (NO₃) reactions with benzene (R-1), toluene (R-2), p-xylene (R-3), p-cresol (R-4) and mesitylene (R-5) have been studied by laser photolysis/long path laser absorption (LP-LPLA) in aqueous solution. Rate constants of k₁=(4.0±0.6) 10⁸, k₂=(1.2±0.3)10⁹, k₃=(1.6±0.1)10⁹, k₄= (8.4±2.3)10⁸ and k₅=(1.3±0.3)10⁹ lmol^-1s^-1 were obtained at T=298 K. In addition, reaction rate coefficients for SO^-₅+Fe²⁺prod. (R-6) and SO^-₅+Mn²⁺prod. (R-7) of k₆=(4.3±2.4) 10⁷ lmol^-1s^-1 and k₇=(4.6±1.0)10⁶ lmol^-1s^-1 (T=298 K, I0) have been obtained by the application of laser photolysis/UV-VIS broadband diode array spectroscopy. A new laser photolysis/UV-long path laser absorption experiment has been applied to study the reaction of the Cl^-₂ radical anion with dissolved sulfur(IV). For the reactions Cl^-₂+HSO^-₃2Cl^-+H⁺+SO^-₃ (R-8) and Cl^-₂+SO^2-₃2Cl^-+SO^-₃ (R-9) rate coefficients of k₈=(1.7±0.2)10⁸ lmol^-1s^-1 (T=298 K, I0) and of k₉=(6.2±0.3)10⁷ lmol^-1s^-1 (T=279 K, I0) were obtained.     

Thermal Behaviour of Metal Complexes of 6-(2-Pyridylazo)-3-acetamidophenol

The present work aims chiefly to study the thermal behaviour of complex compounds with general formula: [M(HL)xH₂O](A)yH₂O (where HL=C₁₃H₁₁N₄O₂=6-(2-pyridylazo)-3-acetamidophenol (PAAP), M=Cu(II), Zn(II), Cd(II) and Fe(III) x=1, 3; y=2, 5) while A=CH₃COO^– (Ac), Cl₂. The second formula is [M(H₂L)xH₂O]Cl₂yH₂O, (where H ₂ L=C₁₃H₁₂N₄O₂ (PAAP), M=Ni(II), Co(II) x=3; y=4, 6). The compounds were identified by elemental analysis, FT-IR spectra and TG/DTG,DTA methods. It was found that during the thermal decomposition of complex compounds water molecules of crystallization are released in the first step. In the next step the pyrolysis of organic ligand takes place. Metal oxide remained as a solid product of the thermal decomposition. Mass spectroscopy has been used for the determination of the thermal decomposition on the intermediate products. It was found that the thermal stability of the studied compounds increases as the ionic radii decreases. The activation energy E, the entropy change S ^*, the enthalpy H ^* change and Gibbs free energy change G ^* were calculated from TG curve.This revised version was published online in November 2005 with corrections to the Cover Date.     

The effect of the network structure of the thermal properties ofcis-1,4-polyisoprene vulcanizates

The thermal properties ofcis-1,4-polyisoprene and its vulcanizates were investigated by means of thermal analysis and complementary methods. It was found that cross-linking generally increases the thermal stability of this elastomer, though distinct differences between peroxide and sulphur vulcanizates were observed. Polysulphide cross-links cleave readily at elevated temperature, and transform to cross-links of lower sulphidity, mainly disulphide. However, some of them are probably oxidized first to sulphoxides, and further to sulphenic or thiosulphoxylic acids. The products formed involve the ionic decomposition of the peroxides and thereby prevent the autocatalytic thermooxidative destruction ofcis-1,4-polyisoprene.

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Zusammenfassung Es wurden die thermischen Eigenschaften voncis-1,4-Polyisopren und dessen Vulkanisaten untersucht. Dabei wurden die Derivatographie und komplementäre analytische Methoden benutzt. Es wurde festgestellt, dass die Vernetzung im allgemeinen die thermische Stabilität von diesen Elastomeren erhöht, obwohl ein ausgeprägter Unterschied zwischen Peroxid- und Schwefelvulkanisaten beobachtet wurde. Die polysulfidischen Brücken wurden bei erhöhter Temperatur leicht gespalten und verwandeln sich in Brücken, die eine niedrigere Schwefelatomzahl besitzen und zwar hauptsächlich disulfidisch sind. Ein Teil der Schwefelatome wurde jedoch wahrscheínlich unter Bildung von Sulfin- und Thio-Sulfoxysäuren oxydiert. Diese Produkte verursachen ionische Zersetzung von Peroxiden und verhindern auf diese Weise die autokatalytische thermooxidative Zersetzung voncis-1,4-Polyisopren.

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-1,4- . , , , , . , , , . , , , . , -1,4 .

     

Synthesis and Structures of the Novel Pyridoxal Oxime Derivatives

Novel pyridoxal oxime derivatives were prepared and characterized by means of IR, ¹H and ¹³C NMR spectroscopy. The crystal structures of the 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1,2-dimethylpyridinium iodide 1 and 3-hydroxy-4-hydroxyiminomethyl-5-hydroxymethyl-1,2-dimethylpyridinium chloride monohydrate 2 were determined by X-ray analysis. The both compounds crystallize in the triclinic crystal system, space group P . Crystal data: 1 a = 6.286(2) Å, b = 8.748(4) Å, c = 11.736(4) Å, = 104.02(3)°, = 94.70(3)°, = 107.44(6)°, V = 589.0(4) ų, Z = 2, R = 0.0526; 2 a = 6.8980(5) Å, b = 8.6409(6) Å, c = 11.1777(6) Å, = 111.138(5)°, = 93.114(6)°, = 105.158(5)°, V = 591.57(7) ų, Z = 2, R = 0.0492. The bond distances and angles in both structures agree very well. The main difference between these structures was observed in the orientation of the hydroxymethyl group with respect to the pyridinium ring. In the both structures intramolecular hydrogen bond forming six-membered ring were observed. The intermolecular OsI hydrogen bonds in the crystal structure of the compound 1 form dimers. In the crystal structure of compound 2, the water molecules and chlorines build eight-membered rings, which are also connected to pyridinium cations by OsCl and OsO intermolecular hydrogen bonds forming a three-dimensional network.     

ESR Spectra of Trifluoromethyl Radical Obtained by Radiolysis and Photolysis in Solid Matrices

The ESR spectrum of CF₃ radicals trapped at 77 K in glassy matrices of a hexafluoropropylene trimer was examined. All the anisotropic components of the spectrum were assigned. The signals from parallel and perpendicular components resulting from hyperfine coupling to fluorine nuclei in the axially symmetrical CF₃ radical were identified. The values of magnetic parameters were found to be A _|| = 25.15 mT, A = 9.1 mT, g _|| = 1.9996, and g = 2.0056. The computer simulated ESR spectrum of CF₃ radical obtained in a glassy hexafluoropropylene trimer matrix can be used to interpret the spectrum of this radical in other solid matrices. Available literature data on the ESR spectra of CF₃ radicals trapped in solid matrices are summarized.