Pyrazine Complexes of Octacyanometallates of Mo(IV) and W(IV) With 8-hydroxyquinoline: Synthesis,characterisation and thermal studies

The complexes formed by photosubstitution of pyrazine (Pz) in octacyanomolybdate(IV) and -tungstate(IV) with 8-hydroxyquinoline have been assigned the formulae [Mo(CN)₂(OH)₂(Pz)₂(OX)] and [W(CN)₂(OH)₂(Pz)₂(OX)·1.5H₂O]. Coordination of Pz as an unidentate ligand by donating a lone pair of electron from nitrogen is shown by an absorption peak between 8–11 µ. Mechanism for the thermal decomposition of the complexes has been given. The formation of tungsten metal as residue in case of II has been confirmed by XRD analysis. The kinetic and thermodynamic parameters like activation energy (E _a), pre-exponential factor (A) and entropy of activation (S ^#) were calculated employing different integral methods of Doyle, Coats and Redfern and Arrhenius.H for each stage of decomposition was obtained from DSC.This revised version was published online in November 2005 with corrections to the Cover Date.     

Preparation and fungitoxicity of 3-bromo-6-chloro- and 6-bromo-3-chloro-8-quinolinols

Summary 3-Bromo-6-chloro- and 6-bromo-3-chloro-8-nitro, -8-amino-, and -8-hydroxyquinolines along with 3-bromo- and 3-chloroquinolin-6,8-diols were prepared and tested for antifungal activity against six fungi (Aspergillus niger, A. oryzae, Myrothecium verrucaria, Trichoderma viride, Mucor cirinelloides, Trichophyton mentagrophytes) inSabouraud dextrose broth. Compounds with chlorine in the 3 position were generally more fungitoxic than the corresponding analogues with bromine. 6-Bromo-3-chloro-8-quinolinol inhibited four fungi at levels below 1 µg/ml andA. niger andM. cirinelloides at 2 µg/ml each.

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Synthese und Fungitoxizität von 3-Brom-6-chlor- und 6-Brom-3-chlor-8-chinolinolen

Zusammenfassung 3-Brom-6-chlor- und 6-Brom-3-chlor-8-nitro-, -8-amino- und -8-hydroxychinoline sowie 3-Brom- und 3-Chlorchinolin-6,8-diole wurden hergestellt und gegen sechs Pilzstämme (Aspergillus niger, A. oryzae, Myrothecium verrucaria, Trichoderma viride, Mucor cirinelloides, Trichophyton mentagrophytes) inSabouraud-Dextrosenährmedium auf lhre fungizide Aktivität untersucht. Verbindungen mit Chlor in Position 3 sind durchwegs fungitoxischer als die entsprechenden Bromanalogen. 6-Brom-3-chlor-8-chinolinol hemmt das Wachstum von vier Pilzen bei Konzentrationen unter 1 µg/ml und das vonA. niger undM. cirinelloides bei einer Konzentration von jeweils 2 µg/ml.

     

8,10-二炔廿五碳酸LB膜的周期结构

合成了8,10-二炔廿五碳酸,在玻璃片、石英片和镀金片上沉积了它的LB膜,X-射线衍射研究了LB膜的周期结构和聚合对它的影响。在2θ=1°—15°范围内观察到了多达7个布拉格衍射峰。由此计算了等同周期和分子在基片上的倾斜角。用分子模型计算了衍射峰强度,得到了与实验结果相符合的衍射峰强度奇偶起伏现象。     

Synthesis and Crystal Structure of 1,7,7-Trimethyl- 4-（4-methoxyphenyl）-4,6,7,8-tetrahydroquinoline- 2,5（1H,3H）-diones under Microwave Irradiation

1 INTRODUCTION Various quinolone derivatives are known to dis- play interesting biological properties ranging from microbial activity to cytotoxicity[1]. They have been reported as antiviral (HIV-1)[2] and antitumor agents[3] as well as used as tubulin[4], topoisomerase[5] and thrombocyte inhibitors[6]. As a member of the quino- lone family, substituted N-phenyl-2-quinolones re-present the structural basis of many biologically active compounds, such as protein kinase inhibitors, immunodu…     

Derivatives of condensed thieno[2,3-d]-pyrimidines. 20. Synthesis of 2-substituted 5,6-dihydro-8H-pyrano[4′,3′:4,5]thieno[2,3-d]pyrimidin-4(3H)-ones and 5,6,7,8-tetrahydrobenzo-[b]thieno[2,3-d]pyrimidin-4-ones

We have developed a method for obtaining 2-substituted 3-amino-6,6-dimethyl-5,6-dihydro-8H-pyrano[4′,3′:4,5]-and 5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-ones, converted by deamination to the corresponding dihydropyranothieno-3H-pyrimidinones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 441–444, March, 2006.     

A novel method for the synthesis of 5,6-dihydro-4H-oxocin-4-ones: 6-endo-dig versus 8-endo-dig cyclizations

The condensation of substituted α-keto alkynes with p-nitrobenzaldehyde in the presence of lithium diisopropylamide (LDA) affords highly substituted 5,6-dihydro-4H-oxocin-4-ones in good yields. Surprisingly, no six-membered carbocycles were formed in this 8-endo-dig cyclization to the oxocinone system.     

Brønsted Acidity and Aluminum Substitution Characteristics of Si(nAi) Sites in Zeolites: A Theoretical MNDO Calculation

The Brønsted acidity of the various Si(nAl) sites present in zeolites is evaluated from proton binding energy and LUMO energy calculated by the semiempirical MNDO quantum chemical method. The two calculated energy values both exhibit a linear correlation with the existing ²⁹Si NMR chemical shift and the IR hydroxyl stretching frequency data. The inter-convertibility between different Si(nAl) sites during an alumination or dealumination process is also evaluated based on the calculated substitution energy. The results indicate that alumination processes are less favorable to occur in zeolites than dealumination processes and the latter is more likely to occur for Si(nAl) clusters that contain the maximum number of aluminum nearest neighbors.     

Novel synthesis and properties of 7,9-dimethylcyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborate: autorecycling oxidation of some alcohols under photo-irradiation

Three-step reactions starting from 2-chlorotropone with barbituric acid afforded novel 7,9-dimethylcyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborate (9·BF₄⁻), which is the isoelectronic compound of the 5-ethyl-3-methyllumiflavinium ion. The stability of cation 9 is expressed by the pK_R+ value, which was determined spectrophotometrically, as ca. 6.0. The electrochemical reduction of 9 exhibited low reduction potential at −0.58 (V vs Ag/AgNO₃), upon cyclic voltammetry (CV). In a search for the reactivity, reactions of 9·BF₄⁻ with some nucleophiles, hydroxide, hydride, amines, thiols, and methanol, were carried out to exhibit that the introduction of nucleophiles is dependent on the nucleophile itself. The photo-induced oxidation reactions of some alcohols catalyzed by 9·BF₄⁻ under aerobic conditions were carried out to give the corresponding carbonyl compounds in more than 100% yield [based on compound 9·BF₄⁻], suggesting the oxidizing function of 9·BF₄⁻ toward alcohols in the autorecycling process. The UV-vis and fluorescence spectra of 9 were studied to suggest the electron transfer from alcohols to the excited 9.     

Zur Bildung und Struktur der Phosphinophosphiniden-phosphorane tBu2P?PP(Me)tBu2 1, tBu(Me3Si)P?PP(Me)tBu2 2 und tBu2P?PP(Br)tBu2 3

Synthesis and Structure of Phosphinophosphinidene-phosphoranes tBu₂P? P?P(Me)tBu₂ 1, tBu(Me₃Si)P? P?P(Me)tBu₂ 2, and tBu₂P? P?P(Br)tBu₂ 3 A new method for the synthesis of 1 and 2 (Formulae see ?Inhaltsübersicht”?) is reported based on the reaction of 5 with substitution reagents (Me₂SO₄ or CH₃Cl). The results of the X-ray structure determination of 1 and 2 are given and compared with those of 3 . While in 3 one P? P distance corresponds to a double bond and the other P? P distance to a single bond (difference 12.5 pm) the differences of the P? P distances in 1 and 2 are much smaller: 5.28 pm in 1 , 4.68 pm in 2 . Both 1 and 2 crystallize monoclinic in the space group P2₁/n (Z = 4). 2 additionally contains two disordered molecules of the solvent pentane in the unit cell. Parameters of 1 : a = 884.32(8) pm, b = 1 924.67(25) pm, c = 1 277.07(13) pm, β = 100.816(8)°, and of 2 : a = 1 101.93(12) pm, b = 1 712.46(18) pm, c = 1 395.81(12) pm, β = 111.159(7)°, all data collected at 143 K. The skeleton of the three P atoms is bent (PPP angle 100.95° for 1 , 100.29° for 2 and 105.77° for 3 ). Ab initio SCF calculations are used to discuss the bonding situation in the molecular skeleton of the three P atoms of 1 and 3 . The results show a significant contribution of the ionic structure R₂P? P(^?)? P(⁺)(X)R₂. The structure with (partially) charged P atoms is stabilized by bulky polarizable groups R (as tBu) as compared to the fully covalent structure R₂P? P(X)? PR₂.     

Ethyl α-cyanoacrylate in the Michael reaction

Ethyl -cyanocarylate undergoes the Michael reaction with strong CH-acids (pK _a < 13) in the presence of strong basic amines such as butylamine, piperidine, and triethylamine. Only polymerization of ethyl -cyanoacrylate occurs under the same conditions with weaker CH-acids in the presence of less basic amines such as aniline, N-methylaniline, and pyridine.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2449–2452, October, 1992.