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71.
Mantel C Hassan AK Pécaut J Deronzier A Collomb MN Duboc-Toia C 《Journal of the American Chemical Society》2003,125(40):12337-12344
The isolation, structural characterization and electronic properties of three new six-coordinated Mn(III) complexes, [Mn(bpea)(F)(3)] (1), [Mn(bpea)(N(3))(3)] (2), and [Mn(terpy)(F)(3)] (3) are reported (bpea = N,N-bis(2-pyridylmethyl)-ethylamine; terpy = 2,2':6',2' '-terpyridine). As for [Mn(terpy)(N(3))(3)] (4) (previously described by Limburg J.; Vrettos J. S.; Crabtree R. H.; Brudvig G. W.; de Paula J. C.; Hassan A.; Barra A-L.; Duboc-Toia C.; Collomb M-N. Inorg. Chem. 2001, 40, 1698), all these complexes exhibit a Jahn-Teller distortion of the octahedron characteristic of high-spin Mn(III) (S = 2). The analysis of the crystallographic data shows an elongation along the tetragonal axis of the octahedron for complexes 1 and 3, while complex 2 presents an unexpected compression. The electronic properties were investigated using a high-field and high-frequency EPR study performed between 5 and 15 K (190-575 GHz). The spin Hamiltonian parameters determined in solid state are in agreement with the geometry of the complexes observed in the crystal structures. A negative D value found for 1 and 3 is related to the elongated tetragonal distortion, whereas the positive D value determined for 2 is in accordance with a compressed octahedron. The high E/D values, in the range of 0.103 to 0.230 for all complexes, are correlated with the highly distorted geometry present around the Mn(III) ion. HF-EPR experiments were also performed on complex 1 in solution and show that the D value is the only spin Hamiltonian parameter which is slightly modified compared to the solid state (D = -3.67 cm(-1) in solid state; D = -3.95 cm(-1) in solution). 相似文献
72.
Anvarhusein A. Isab Abdul R. Al-Arfaj Mohammed Arab Mir M. Hassan 《Transition Metal Chemistry》1994,19(1):87-90
Summary Pd(CN)2 reacts with imidazolidine-2-thione (Imt), 1,3-diazinane-2-thione(Diaz), 1,3-diazipnane-2-thione (Diap) and their derivatives to yield complexes of stoichiometry [PdL2(CN)2] or [PdL(CN)2] (L = Imt, Diaz or Diap and L = Imt having N-Me, Et or Pr substituents), which were characterized by elemental analysis, i.r., 1H and 13C n.m.r. spectroscopy. Both mono- and bis ligand complexes are thought to be square planar with the monoligand binding to metal via sulphur (bridging) and the bis ligand via the monodentate thione group. The 13C enriched Pd(13CN)2 complex was prepared and the 13C n.m.r. recorded. The C-2 resonance of 13C n.m.r. of Imt, Diaz or Diap complexes of the copper(I), silver(I), gold(I) and palladium(II) were compared. 相似文献
73.
Summary New complexes of chromium(III), manganese(II) and nickel(II) with methylhydrazinecarboxylate (MeCz) and of manganese(II) and
nickel(II) with 1,1-dimethylhydra-zinecarboxylate (Me2Cz) were prepared by reacting salts of the metals with CO2-saturated solutions of the hydrazines in EtOH. The compounds [Cr(MeCz)3]·2H2O, Ni(MeCz)2(H2O)3·MMH, Mn(MeCz)2(H2O)2(MMH = monomethylhydrazine) and M(Me2Cz)2(H2O)2 (M = Mn or Ni) were investigated using d.t.a., t.g.a., electronic and i.r. spectroscopy and by magnetic susceptibility measurements. 相似文献
74.
Hassan Sheibani 《Tetrahedron》2004,60(28):5931-5934
2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time. 相似文献
75.
M. S. K. Youssef Kh. M. Hassan F. M. Atta M. S. Abbady 《Journal of heterocyclic chemistry》1984,21(5):1565-1568
3-Hydrazino-7-methyl-5-phenyl-5H-pyrazolo[3,4-c]-as-triazine 1 underwent ring closure and/or condensation reaction with formic acid, acetic acid, acetic anhydride and benzoyl chloride to afford 1H-pyrazolo-[3,4-d]-s-triazolo[3,4-c]-as-triazines 2, 5 and 7a and/or N-acyl derivatives 3, 4 and 6 . N-Acyl derivatives 3 and 6 underwent cyclisation reaction on treatment with phosphoryl chloride to give 5 and 7a . 3-Methyl-1-phenyl-8-aryl-1H-pyrazolo[3,4-e]-s-triazolo[34,-c]-as-triazines 7 were also prepared by the reaction of the hydrazono derivatives 8 wit thionyl chloride. On treatment of 1 with nitrous acid gave the 8H-pyrazolo[3,4-e]tetrazolo-[5,1-c]-as-triazine 9 . Compound 1 underwent ring closure with carbon disulphide or ethyl chloroformate to 1,7-dihydro-8H-pyrazolo[3,4-e]-s-triazolo[3,4-c]-as-triazine derivatives 10 and 12 . Reaction of 1 with ethyl acetoacetate or acetylacetone gave 3-pyrazolo derivatives 13 and 14 . 相似文献
76.
A simple, rapid and sensitive spectrophotometric method is described for the quantitative determination ofN-substituted phenothiazines. The method depends on the formation of a stable phenothiazine free radical cation by the use ofN-bromophthalimide as oxidising agent in a strong acid medium (methanol/ sulphuric acid 1 1 v/v). The produced red or violet color possesses absorption maximum range from 500 to 530 nm. A linear relationship exists between the absorbance at (max) and concentration in the range 5 to 40 g ml–1 with apparent molar absorptivities range from 6 × 103 to 12 × 1031 mol–1 cm–1. The color is developed instantaneously for all the studied phenothiazines except for thioproperazine mesylate, trifluoperazine dihydrochloride and prochlorperazine mesylate that require 25, 15 and 25 min, respectively, for complete reaction. The developed colors are stable over 24 h. The average % recovery is 99.85±0.61 to 100.28±0.95. The method was applied successfully to the microdetermination of chlorpromazine HCl, promethazine HCl, pericyazine, thioproperazine mesylate, perphenazine, prochlorperazine mesylate, trimeprazine tartrate and trifluoperazine 2HCl either in pure form or incorporated in their pharmaceutical preparations. The results of analysis are in good agreement with those of the official B.P. 1988 and USP XXII. 相似文献
77.
M. Amin H. H. Hassan E. M. Abdel-Bary 《Journal of polymer science. Part A, Polymer chemistry》1974,12(11):2651-2657
Styrene–butadiene rubber (SBR) charged with 50 phr of HAF carbon black has been found to show a positive temperature coefficient of resistivity close to 0.07/°C at 27°C. Beyond a point (75°C) of minimum conductivity, however, it behaves as a normal noncrystalline semiconductor with a resistivity which decreases with rise of temperature with an activation energy of 0.56 eV. Blending the composition with poly(vinyl chloride) (PVC) shifts the minimum towards lower temperatures. The descending branch of the conductivity versus reciprocal absolute temperature characteristic is probably associated with thermal expansion of tunnelling paths separating the conducting carbon particles. 相似文献
78.
Refat M. Hassan 《Journal of polymer science. Part A, Polymer chemistry》1993,31(5):1147-1151
The kinetics of decomposition of [Alg · Mn VIO42?] intermediate complex have been investigated spectrophotometrically at a constant ionic strength of 0.5 mol dm?3. The decomposition reaction was found to be first-order in the intermediate concentration. The results showed that the rate of reaction was base-catalyzed. The kinetic parameters have been evaluated and found to be ΔS? = ?103.88±6.18 J mol?1 K?1, ΔH? = 51.61 ± 1.02 kJ mol?1, and ΔG? = 82.57 ± 2.86 kJ mol?1, respectively. A reaction mechanism consistent with the results is discussed. © 1993 John Wiley & Sons, Inc. 相似文献
79.
H. A. Azab A. M. El-Nady A. Hassan R. S. A. Azkal 《Monatshefte für Chemie / Chemical Monthly》1994,125(10):1059-1066
Summary Potentiometric equilibrium measurements have been made for the interaction of adenosine-5-mono-,-di-, and -triphosphate, and Co(II) with biologically important secondary ligands (malic, maleic, succinic, tartaric, citric, and oxalic acid). The formation of various 1:1:1 mixed ligand complexes inferred from the potentiometric titration curves. Initial estimates of the formation constants of the resulting species and the acid dissociation constants ofAMP,ADP,ATP and the secondary ligand acids have been refined with a computer program. In some systems, the ternary complexes are found to be more stable than the corresponding binary ones. In some ternary systems studied, interligand interactions or some cooperativity between the coordinate ligands, possibly H bond formation, have been found to be most effective in deciding the stability of the complexes formed in solution. Stabilities of mixed ligand complexes increase in the orderAMP <ADP <ATP. With respect to the secondary ligands, the formation constants of the mixed ligand complexes decrease in the following order: succinic > maleic > tartaric > malic > citric > oxalic acid.
Potentiometrische Untersuchung der Bildungsgleichgewichte von binären und ternären Komplexen von Kobalt(II) mit Adenosin-5-mono-, -di- und -triphosphat und einigen biologisch bedeutenden polybasischen Sauerstoffsäuren
Zusammenfassung Die Wechselwirkung vonAMP,ADP undATP mit Co(II) und einigen biologisch interessanten Sekundärliganden (Bernsteinsäure, Hydroxybernsteinsäure, Maleinsäure, Weinsäure, Zitronensäure und Oxalsäure) wurde bei 25°C und einer lonenstärke von 0.1M KNO3 potentiometrisch untersucht. Die Titrationskurven zeigen das Vorliegen von Species der Zusammensetzung 1:1:1 an. Die geschätzten Bildungskonstanten der Komplexe und die Dissoziationskonstanten der Liganden wurden mittels eines Computerprogramms optimiert. In einigen der untersuchten Systeme sind die ternären Komplexe stabiler als die sekundären. Die Stabilität der Verbindungen hängt im wesentlichen von Interligandwechselwirkungen — möglicherweise der Ausbildung von Wasserstoffbrückenbindungen — ab. Die Stabilität der Komplexe mit gemischten Liganden steigt in der ReihenfolgeAMP <ADP <ATP und fällt entsprechend der Serie Bernsteinsäure > Maleinsäure > Weinsäure > Hydroxybernsteinsäure > Zitronensäure > Oxalsäure.相似文献
80.
Mohamed Hilmy Elnagdi Mohamed Riffaat Hamza Elmoghayer Hassan Attia Elfaham Mohamed Mohamed Sallam Hikmat Hussein Alnima 《Journal of heterocyclic chemistry》1980,17(2):209-212
The 4-bromo-3-phenylpyrazol-5-ylhydrazonyl chlorides (Ia,b) and 1,2,4-triazol-5-ylhydrazonyl chlorides (IIa,b) were prepared via coupling of diazotized 4-bromo-3-phenyl-5-aminopyrazole (III) and 5-amino-1,2,4-triazole (IV) with α-chloro derivatives of acetylacetone and of ethyl aceto-acetate. Compounds Ia and IIa,b were utilised for the synthesis of several new heterocyclic derivatives. 相似文献