Reaction of Ru3(CO)12 with 1,3-diferrocenylprop-2-ene-1-one. Crystal and molecular structures of the complexes Ru3(CO)8(FcC=CHCOFc)2 and [Ru(CO)2Cl(FcC=CHCOFc)]2

The reaction of Ru₃(CO)₁₂ with 1,3-diferrocenylprop-2-en-1-one,trans-FcCH=CHCOFc (where Fc is ferrocenyl), in boiling hexane afforded the complex (2c), which was converted into (3c) upon further heating. These complexes gave the complex (4) containing two Cl-bridged oxaruthenacycles upon dissolution in CHCl₃ or CH₂Cl₂. The structures of complexes 3 and 4 were established by X-ray diffraction analysis. According to the data of¹H NMR spectroscopy, the Cl-bridged complex exists in solutions as a mixture of isomers along with the monomeric form resulting from the cleavage of the halide bridges. All interconversions of the isomers occur with the participation of the monomeric form. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1616–1623, September, 2000.     

Ab initio study of the complexes of first-row transition-metal ions with CH, CH2, and CH3

The geometries and bonding characteristics of the complexes of the first-row transition-metal ions with CH, CH₂ and CH₃ were investigated byab initio molecular orbital theory. MCH⁺ and MCH₂ ⁺ are linear and coplanar, respectively. Both of them are with obvious treble or double bond characteristics, but these multiple bonds are mostly “imperfect”. The calculated bond dissociation energies of , and are mostly close to the experimental values, and appear in similar periodic trends from Sc to Zn. Project supported by the National Natural Science Foundation of China (Grant No. 29170070).     

Fourier Transform and Multi Dimensional EPR Spectroscopy for the Characterization of Sol-Gel Derived Hydroxyapatite

Calcium hydroxyapatite powder was prepared by sol-gel method using calcium acetate and PO(OC₂H₅)₃ as initial compounds, and alcohol (methyl, ethyl, and propyl-alcohol) as solvent. Homogeneous solution and gels were prepared using a molar ratio of Ca/P=1.67. The evolution of the structure was detected by X-ray diffraction, IR, and FT-n(=1,2,3)D-EPR spectroscopy. The dried gels exhibit a signal characterized by a central line and two satellites. The 2D spectrum (ESEEM vs. field sweep) showed the same modulation for the central line. The FT-EPR spectrum vs. field sweep 2D-spectrum indicated that the satellites are due to an hfs splitting with water. The central region of this 2D spectrum is influenced by P and H in a concentration ratio of [H]/[P]=2.5. The ESEEM spectrum was simulated assuming the equation V_mod=V_mod(P)^mV_mod(H)ⁿ for two spin systems S=1/2 and I=1/2. This simulation gave form andn the values of 2 and 5, respectively. This finding suggests the structure: for the unpaired state. It appears that one ethyl group does not hydrolyse in the gelation process. The ESEEM spectra of hydroxyapatite exhibit a modulation generated by P, H and Ca atoms.     

Parallel synthesis of novel benzimidazoles on a soluble polymer support

Liquid phase combinatorial synthesis using a soluble polyethylene glycol (PEG) polymer support and commercially available 3-nitro-4-fluoro benzoic acid is carried out in order to create a molecular library of trisubstituted benzimidazoles. The PEG-ester conjugate of 3-nitro-4-fluoro benzoic acid is subjected to ipso-fluoro displacement by various primary amines. The nitro group is reduced under neutral conditions using excess zinc and ammonium chloride, producing the polymer-boundo-phenylene diamines. Reaction of the diamines with different aldehydes results in cyclisation to benzimidazoles. The polymer support is cleaved releasing the desired products in high yields and purity. All reactions are performed at room temperature.      

A new type of polarographic catalytic wave of organic compound

The polamgraphic behavior and catalytic wave mechanism of medroprogestemne acetate (MPA) were studied in both aqueous and DMF media. In 0.2 mol/L acetic acid-sodium acetate (pH 5.0) buffer solution, the bond of MPA first undergoes le, lH⁺ reduction to form protonated free radical HMPA, the further reduction of HMPA in le,1H⁺ process is simultaneous with the dimerization reaction between HMPA and neutral molecular MPA. In DMF media containing 0.1 mol/L tetrabutylammonium tetrafluoborate (TBA.BF₄), the bond of MPA shows two le, 1H⁺reduction waves, which are ascribed to the reduction of MPA and free radical MPA.^-, respectively. Here, no dimerization reaction occurs. These processes produce the reduction wave of MPA. In the presence of oxidant KIO₃,a polamgraphic catalytic wave of MPA is observable due to a chemical reaction between HMPA. or MPA.^- and KIO₃ as well as its intermediate species to regenerate MPA. The catalytic wave, which is caused by the reduction of organic compound itself and the chemical reaction between oxidant and organic intermediate free radical to regenerate original organic compound, is a new-type wave of organic compound. Under optimum experimental conditions, the sensitivity of MPA catalytic wave in the presence of KIO₃ is an order of magnitude higher than that of its reduction wave. The catalytic wave can be used for analytical purpose. The calculated rate constant of catalytic reaction is 1.7 × 10³ mol·L^-1·s^-1. Project supported by the National Natural Science Foundation of China (Grant No. 29875017).     

Structural transformations during the gas chromatography of carbamates

Summary There is no apparent paucity of examples illustrative of the structural changes observed during the gas chromatography of diverse carbamates and thiocarbamates. In many cases the resultat thermal degradation products observed are analogous in some measure to the three possible modes of decomposition reported in nonchromatographic thermal studies for N-phenyl carbamates [4, 35, 36], e.g., Dyer andWright [35] have shown that when R is a primary or secondary alkyl group, all three modes of decomposition can occur when the reaction is carried out in the absence of solvents. If the amine and isocyanate products are allowed to remain in the formation mixture, diphenyl urea is also formed, viz., As has been shown, the thermal and hydrolytic stabilities of carbamates exhibit a marked dependence upon the degree and type of N-substitution. Disubstituted carbamates are quite resistant to thermal decomposition (as well as hydrolysis). Monosubstituted carbamates readily undergo thermal decomposition at elevated temperatures to yield primarily the respective isocyanate while unsubstituted carbamates have been reported to decompose to allophanates, cyanuric acid, and alcohol [37]. The thermal decomposition of unsubstituted carbamates is accelerated appreciably in the presence of eventrace amounts of metal salts, giving rise to the formation of cyamelide. The degradative scheme for the diol dicarbamates (as typified by the medicinal carbamates, meprobamate and soma) is more difficult to interpret.Paquin [38] reported that the pyrolysis of the dicarbamate of 1,3-butylene glycol (I), yielded an oxazolidone (II) and a cyclic urea (III) as follows: The further degradation of compounds II and III under pyrolytic conditions remains a distinct possibility.

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Strukturumwandlungen w?hrend der Gas-Chromatographie von Carbamaten

Zusammenfassung Es besteht offenbar kein Mangel an Beispielen für Strukturumwandlungen w?hrend der Gas-Chromatographie verschiedener Carbamate und Thiocarbamate. In vielen F?llen entsprechen die beobachteten resultierenden thermischen Abbauprodukte in gewissem Ma?e den drei m?glichen Abbauformen, über die in nichtchromatographischen thermischen Untersuchungen von N-Phenylcarbamaten berichtet wird [4, 35, 36], z.B. Dyer Wright [35] haben gezeigt, da?, wenn R eine prim?re oder sekund?re Alkylgruppe ist, alle drei Abbauformen vorkommen k?nnen, wenn die Reaktion in Abwesenheit von L?sungsmitteln stattfindet. Wenn die Amin- und Isocyanat-Produkte in der Mischung belassen werden, bildet sich auch Diphenylharnstoff, n?mlich: Wie gezeigt wurde, besitzt die thermische und hydrolytische Stabilit?t von Carbamaten eine starke Abh?ngigkeit von Grad und Art der N-Substitution. Disubstituierte Carbamate sind ziemlich resistent gegen therm?sche Zersetzung (wie auch gegen Hydrolyse). Monosubstitutierte Carbamate lassen sich bei h?heren Temperaturen leicht thermisch zersetzen, wobei haupts?chlich das entsprechende Isocyanat entsteht, w?hrend sich unsubstituierte Carbamate nach [37] in Allophanate, Cyanurs?ure und Alkohol zersetzen. Der thermische Abbau unsubstituierter Carbamate wird durch Anwesenheit selbst geringer Spuren von Metallsalzen nennenswert beschleunigt, wobei Cyamelid entsteht. Das Abbauschema für die Diol-Dicarbamate (typische Beispiele: medizinische Carbamate, Meprobamat und Soma) ist schwieriger zu interpretieren.Paquin [38] berichtet, da? bei der Pyrolyse des Dicarbamats von 1,3-Butylenglycol (I) ein Oxazolidon (II) und ein cyclischer Harnstoff (III) in der folgenden Weise entstanden: Der weitere Abbau der Verbindungen II und III unter Pyrolysebedingungen ist nicht auszuschlie?en.

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Transformations de structure pendant la chromatographie en phase gazeuse de carbamates

Sommaire On ne manque pas d'exemples qui illustrent les transformations de structure observées pendant la chromatographie en phase gazeuse de divers carbamates et thiocarbamates. Souvent les produits de dégradation thermiques obtenus sont analogues, dans une certaine mesure, a ceux formés par décomposition thermique selon un des schémas probable signalé ci-après, procédés qui furent decrits pour des carbamates N-phényliques [4, 35, 36] dans des études de stabilité thermique non-chromatographiques, par exemple: Dyer etWright [35] ont démontré, si R est un groupe alkyle primaire ou secondaire, les trois modes de décomposition peuvent avoir lieu si la réaction se produit en l'absence de solvants. Si les amines et les isocyanates sont laissés dans le mélange, il y a aussi formation de diphénylurée, c'est-à-dire Il a été montré que la stabilité thermique et hydrolytique de carbamates dépend fortement du degré et type de la N-substitution. Des carbamates disubstitués sont assez résistants à la décomposition thermique (ainsi qu'à l'hydrolyse). Les carbamates monosubstitutés sont facilement sujets à la décomposition thermique à des températures élevées, produisant surtout l'isocyanate correspondant, tandis que, selon la littérature, des carbamates non-substitués sont décomposés en formant des allophanates, acide cyanurique, et alcool [37]. La décomposition thermique de carbamates non-substitués est accélérée sensiblement par la présence de sels métalliques, même à l'état de trace, provoquant la formation de cyamélide. Le schéma de dégradation des diol-dicarbamates (exemples typiques: carbamates médicinaux, méprobamate, soma) est plus difficile à interpréter.Paquin [38] a trouvé que la pyrolyse du dicarbamate de 1,3-butylène glycol (I) produit un oxazolidone (II) et une urée cyclique (III) d'après le schéma suivant: La dégradation ultérieure des composés II et III sous des conditions pyrolytiques n'est pas à exclure.

     

Synthesis,structures and properties ofN-(trihalogermylmethyl)-substituted amides,lactams and imides,the derivatives of the five-coordinate germanium

The formation of trichlorogermyl-substituted amides, lactams, and imides occurs when 2Et₂O·HGeCl₃ is condensed with compounds possessing the -NCH₂Cl fragment and equally well when HGeCl₃ interacts with compounds containing -NCH₂OH and-NCH₂OSiMe₃ groups. In some cases, the use of the latter is more advantageous from the preparative point of view. In compounds thus obtained, the germanium is five-coordinate due to the coordination . Deceased August 13, 1993. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1793–1799, October, 1993.     

Heteroorganic betaines

The [Ph₃P⁺−CMe₂−SiMe₂−SEt]Br⁻ salt was prepared by the reaction of betaine Ph₃P⁺−CMe₂SiMeR−S⁻ (1a: R=Me) with EtBr. Acetylation of betaine1a or Et₃P⁺−CHMeSiMe₂−S⁻ (2a) afforded 2,2,6-trimethyl-1,3-dioxa-2-silacyclohex-5-ene-4-thione      

UV photolysis of protonated ruthenium and osmium decamethylmetallocenes as a new method for synthesis of the metallonium cations

Decamethylmetallocenes Cp^* ₂M (M=Ru, Os) in the presence, of acids (CF₃CO₂H, CF₃SO₃H) give thepprotonation products [Cp^* ₂MH]⁺An⁻. Broad-band UV photolysis of their solutions results in the formation of the salts of onium cations . A preparative procedure for the synthesis of these salts has been developed. Hydrolysis of the salts gives the carbinol Cp^*MC₅Me₄CH₂OH. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 587–591. March, 1999.     

Synthesis and catalytic activity of Ln (<Emphasis Type="Bold">III</Emphasis>) complexes with an unsymmetrical Schiff base including multi groupsgroups

A synthetic method for a new unsymmetrical Schiff base and its Ln (III) complexes including multi groups is reported. The complexes are characterized by elemental analysis, IR spectra, ¹H and¹³C NMR, especially 2D-COSY ¹H, ¹H NMR spectra. The general formula of the obtained complexes is [Ln₃(TBLY)(NO₃)₃]\sdnH₂O (Ln = La, n = 3; Ln = Nd, n=5; Ln = Gd, Dy, Yb, Y, n = 7), where TBLY = tetraglycol aldehyde-2,4-dihydroxy benzaldehyde bis-lysine Schiff base. In addition, the evidence for existence of group is supported by the AM1 method. The complexes obtained may be used as a catalyst. Conversion rate of 80% with the viscosity-average molecular weight 220000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst has been obtained.     

Benzidine and diphenylamine radical formation on the surface of NaY-zeolite and γ-alumina with and without V2O5

Solutions of benzidine and diphenylamine in benzene produce cation radicals on the surface of zeolite, -alumina and V₂O₅ doped alumina and zeolite. The sequence of the electron acceptor site strength on the surface is as follows:     

Relations entre structure chimique et grandeurs de retention. VII. Composés de structure cyclopropanique

Résumé Les auteurs ont étudié le comportement chromatographique sur plusieurs phases stationnaires polaires et non polaires de composés cyclopropaniques stéréoisomêres: où R=H ou CH₃ et X=CH, COOCH₃ ou CH₂OH. Les résultats sont interprétés en fonction de la configuration de X par rapport à , de la nature électronique de X et de l'orientation du phényle par rapport au plan du cyclopropane.

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Relationship between chemical structure and retention. VII. Cyclopropane compounds

Summary The chromatographic behaviour, on several polar and non polar phases, of stereoisomeric cyclopropanes has been studied R=H or CH₃ and X=CN, COOCH₃, CH₂OH. The results are interpreted in terms of the X versus configuration, the electronic nature of X and the orientation of the phenyl ring in relation to plane of the cyclopropane ring.

     

Studies on the synthesis and thermal decomposition mechanisms of rare-earth metal (Pr,Nd, Sm) salt hydrates of 3-nitro-1,2,4-triazol-5-one

Three new rare-earth metal (Pr, Nd and Sm) salt hydrates of 3-nitro-1,2,4-triazol-5-one (NTO) were prepared and characterized. The thermal behaviour of the three salt hydrates, M(NTO)₃·nH₂O (M=Pr and Nd,n=9;M=Sm,n=8) were studied by means of TG and DSC under conditions of linear temperature increase. The thermal decomposition intermediates were determined by means of IR, MS and X-ray diffraction spectrometry. The thermal decomposition mechanisms of these hydrates were proposed as follows: We express our thanks to Professor Zhu Chunhua, Associate Professor Fu Xiayun, and Lecturers Fan Tao and Liang Yanjun for their help in this work.     

Ternary surface complexes by theE(%)-pH curve method

A new method for the study of ternary surface complexes at liquid-solid interface, theE(%) -pH curve method, was proposed. Four types ofE(%)-pH curves, namely, phenomenon of left-right shifts of S-shaped curve, V-shaped curve, monodirection shift curve and X-shaped curve, were discovered. Correspondingly, apart from type (I) ternary surface complex and type (II) ternary surface complex , a new type of ternary surface complex was discovered. Project supported by the National Natural Science Foundation of China and the Fund of Doctoral Degree’s Spot.     

Synthesis of [D-phe3 (NH2); Pro3; D-Ala6]- and [D-Phe2 (NO2); Pro3; D-Ala6]luliberins

In order to study the influence of substituents of the aromatic ring of D-phenyl-alanine on the inhibiting capacity of luliberian analogs, we have synthesized two new analogs: and luliberin. The synthesis was performed by the fragmentary condensation method using 2+(3+5) and 2+(5+3) schemes. A new and convenient method of obtaining the amide of the C-terminal tetrapeptide of the luliberin sequence has been developed. In the condensation of the fragments, both the azide and the carbodimide method of synthesis with the addition of l-hydroxybenzotriazole were used. The guanidino group of arginine was protected by nitration, while the hydroxy groups of serine and of tyrosine were not protected. The complete elimination of the protective groups from the decapeptides was performed by catalytic hydrogenation over Pd on carbon and by anhydrous HF with the addition of anisole at 0°C. The protected octa- and decapeptides were purified by gel filtration on Sephadex LH-20 in ethanol or by preparative thin-layer chromatography on silica gel plates. The final peptides were purified by ion-ex-exchange chromatography on Sephadex CM-25. A. A. Zhdanov Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 706–714, September–October, 1980.     

Paramagnetic centers by X-ray-irradiation of aluminium hydroxide

EPR spectra of paramagnetic centers originating from X-ray-irradiation of aluminium hydroxide at room temperature have been measured. The EPR spectrum represents a superposition of EPR spectra of ionic centers O^–, holes of type and trapped electrons. Radiation chemical yield of paramagnetic centers observed at room temperature (293 K) is G(spins.)=4.4±0.6) spins per 100 eV absorbed energy. The decay of paramagnetic centers in irradiated Al(OH)₃ was oberved at 293 K. The rate constant of the paramagnetic centers decay in irradiated Al(OH)₃ is K₂=(0.0980±0.0019) kg·mol^–1·min^–1 and their half-life is 9.43±0.18 days.Dedicated to the memory of the late Genrikh Markovis Kolyiari.     

New accessory for studies of isotopic 1H/2H exchange and biomolecular interactions using transmission infrared spectroscopy

We present here a new accessory for IR transmission measurements of ¹H/²H exchange, as an ancillary tool for monitoring structural features of biomolecules in aqueous solution. This new accessory results from the combination of two dialysis membranes and a conventional liquid cell having two cylinders containing ²H₂O buffer. When compared with conventional transmission measurements, carried out either after dissolving lyophilized biomolecules in ²H₂O or after dialyzing the aqueous solution considered against ²H₂O buffer, this accessory shows the following advantages: (1) controlled measurements over the initial steps of this isotopic exchange and absence of molecular aggregation, and (2) smaller sample amounts. This new Fourier transform IR cell can also be used to analyze ligand–biomolecule and drug–cell interactions.      

Potentiometric study of the formation of hydroxo complexes of [Cu(terpy)]2+. Synthesis and crystal structure of [Cu(terpy) (H2O)](CF3SO3)2

Two complexes of formula [Cu(terpy)(H₂O)](CF₃SO₃)₂ (1) and [Cu(terpy)(OH)]BPh₄ (2) (terpy=2,2′∶6′,2″-terpyridine and BPh₄=tetraphenylborate anion) have been synthesized and characterized by spectroscopic techniques. The x-ray crystal structure of (1) has been determined by x-ray diffraction. The structure is made up of [Cu(terpy)(H₂O)]²⁺ mononuclear cations plus semi-coordinated CF₃SO₃ ⁻ anions. The coordination geometry around the copper atom is approximately elongated tetragonal octahedral. The oxygen atom of water and the three nitrogen atoms of terpy occupy the equatorial sites whereas the apical ones are filled by trifluoromethanesulphonate oxygen atoms. The formation of hydroxo complexes of [Cu(terpy)(H₂O)]²⁺ has been investigated by potentiometry in aqueous solutions and the constants of the Equilibria (1) and (2)      

Mechanism of the long wavelength photolysis of CS2 vapor

It is proposed that in the long wavelength (λ ≥ 290 nm) photolysis of CS₂ vapor the observed CS and S₂ are produced in the reaction sequence:      

Heteroorganic betaines

Photolysis and thermal decomposition of betaines R₃P−CR¹R²−SiR³R⁴−S⁻ (1) follows two main pathways: (a) a Corey—Chaykovsky type reaction with elimination of Ph₃P and generation of silathiirane (2) and (b) a retro-Wittig type reaction accompanied by elimination of R₃P=CR¹R² and generation of silanethione R³R⁴Si=S (3). Highly reactive compounds2 and3 undergo subsequent transformations to give derivatives of tetrahydro-1,4-dithia-2,5-disilin, 1,3-dithia-2,4-disilolane, and phosphonium salts ofsymm-tetraorganodisilthiane dithiolates [Ph₃P⁺CHR¹R²]₂[(R³R⁴SiS⁻)₂S]. The structures of the compounds obtained were established by X-ray diffraction analysis and multinuclear NMR spectroscopy. For part 3, see Ref. 1. The betaines Et₃P⁺CHMeSiMe₂S⁻ and Et₃P⁺CHMeSiPh₂S⁻ with alkyl groups at the phosphorus atom are distinguished by high thermal stability; their spectral characteristics do not change during storage of solutions of these compounds in pyridine-d₅ or metastable solutions in benzene-d₆ for 1–2 years at −20°C in sealed evacuated tubes or on heating (150°C) for 15 h. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1594–1603, September, 2000.