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1.
The effect of dielectric constant on ion association of triethylammonium picrate and methylimidazolium picrate and on ion-ligand complex formation between the cations Et3NH+ and MeImH+ and 1-methylimidazole was investigated from conductance data carried out in nitrobenzene-benzene mixtures (34.8K
A
satisfy in first approximation the relation logK
A
1/D. The center-to-center distance å has been calculated and compared to the value obtained for nonhydrogenbonded ion pairs. The ion-ligand association constantK
1
+
increases as the dielectric constant of the medium decreases. Plots of logK
1
+
against 1/D give straight lines, the slopes of which are consistent with the predictions of a theory that interprets the effect of the dielectric constant in terms of changes in the polarization energy of the solvent around the complexed and the uncomplexed ions. For these interactions, the complexed ions can be approximated as charged spheres, the volume of which is equal to that of the bare ion plus the volume of the ligand. 相似文献
2.
Niloofar Tavakoli‐Hoseini Raheleh Moloudi Abolghasem Davoodnia Mohammad Shaker 《中国化学》2011,29(11):2421-2426
A convenient and efficient method for the synthesis of pyrazolo[3,4‐d]pyrimidin‐4‐ones via heterocyclization reaction of 5‐amino‐1H‐pyrazole‐4‐carboxamides with triethyl orthoesters using two Br?nsted‐acidic ionic liquids, 3‐methyl‐1‐(4‐sulfonic acid)butylimidazolium hydrogen sulfate [MIM+(CH2)4SO3H][HSO4?] or N‐(4‐sulfonic acid)butyl triethylammonium hydrogen sulfate [Et3N+(CH2)4SO3H][HSO4?], as efficient homogeneous catalysts under solvent‐free conditions is described. 相似文献
3.
The data on coadsorption of tetraethylammonium (Et4N+), tetrapropylammonium (Pr4N+), and tetrabutylammonium (Bu4N+) cations with Cl–, Br–, and I– anions on an uncharged mercury electrode are compared with the models of coadsorption in a common monolayer and two parallel layers. The second model is shown to be in best agreement with experimental isotherms. However, the least discrepancy between calculations and experimental results is obtained when coadsorption of mentioned cations and anions is described by the Frumkin isotherm for neutral molecules with certain effective adsorption parameters. 相似文献
4.
Jun Ni Yi‐Zhi Li Zheng Xue Hui‐Lan Chen Zhi‐Lin Wang 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):m201-m203
The title complex, bis[3,3′‐(pyridine‐4‐imino‐κN1)dipropanenitrile]silver(I) perchlorate, [Ag(CEAP)2]ClO4 {CEAP is 4‐[N,N‐bis(2‐cyanoethyl)amino]pyridine, C11H12N4}, has been prepared and characterized. The unit cell consists of two crystallographically non‐equivalent molecules. Cation cavities are constructed by [Ag(CEAP)2]+ cations through hydrogen bonds, and the ClO4− anions are incorporated into the cavities in μ4‐ and μ2‐ClO4− bridging modes through C—H⃛O hydrogen bonds. 相似文献
5.
Ultrasonic absorption data obtained over the frequency range 5–95 MHz by the pulse method are reported for tetraethylammonium bromide, 1,5-bis-(triethylammonium) pentane dibromide and 1,10-bis(triethylammonium) decane dibromide in 2-propanol in the temperature range 0–25°C. A single relaxation curve is observed under all experimental conditions. The relaxation frequencies depend linearly on the salt concentrations. The excess absorption of these three salts in 2-propanol is mainly attributed to an ion association process. The thermodynamic and kinetic parameters of (Et)
4
NBr in 2-propanol were obtained from the ultrasonic data and previously published conductance data. The difference between the behavior of Et
4
NBr and the bolaform salts is discussed. 相似文献
6.
Sana Zama Abdelmalek Bouraiou Sofiane Bouacida Thierry Roisnel Ali Belfaitah 《Tetrahedron letters》2013
A new class of thiazolo[3,2-a]imidazole derivatives is obtained in good yields, by reacting 1-methyl-2-bromoimidazolium salts bearing N+-CH2COAr, N+-CH2COMe, N+-CH2COOMe, or N+-CH2CN fragments, with carbon disulfide in the presence of Et3N at room temperature. The mesoionic structures of these compounds are established by NMR spectroscopy and by single-crystal X-ray analysis. 相似文献
7.
Pier G. Daniele Alessandro De Robertis Concetta De Stefano Silvio Sammartano 《Journal of solution chemistry》1989,18(1):23-36
Imidazole protonation constants were determined potentiometrically, using a (H+)-glass electrode, in LiCl, NaCl, KCl, CaCl2, MgCl2, tetramethylammonium (Me4N-) iodide and chloride, Et4N-, Pr4N- and Bu4N-iodides. Salt effects were tentatively explained by assuming that complexes [H(Im)X]o (Im = imidazole, X–=Cl– or I–), [M(Im)]2+ (M2+=Mg2+ or Ca2+) and [A(Im)]+ (A+ = tetraalkylammonium cation) were formed in solution. Calcium(II)-selective electrode measurements confirmed our hypothesis about the formation of the Ca2+-imidazole complex. The reliability of the complex formation model is discussed on the basis of its self consistency and in light of previous results. 相似文献
8.
S. N. Dmitrieva M. V. Churakova N. A. Kurchavov A. I. Vedernikov L. G. Kuz’mina A. Ya. Freidzon A. A. Bagatur’yants Yu. A. Strelenko J. A. K. Howard S. P. Gromov 《Russian Chemical Bulletin》2010,59(6):1192-1206
A number of N-alkylnitrobenzoaza-15-crown-5 with the macrocycle N atom conjugated with the benzene ring were obtained. The structural and
complexing properties of these compounds were compared with those of model nitrobenzo- and N-(4-nitrophenyl)aza-15-crown-5 using X-ray diffraction, 1H NMR spectroscopy, and DFT calculations. The macrocyclic N atom of benzoazacrown ethers are characterized by a considerable
contribution of the sp3-hybridized state and a pronounced pyramidal geometry; the crownlike conformation of the macrocycle
is preorganized for cation binding, which facilitates complexation. The stability constants of the complexes of crown ethers
with the NH4
+, EtNH3
+, Na+, K+, Ca2+, and Ba2+ ions were determined by 1H NMR titration in MeCN-d3. The most stable complexes were obtained with alkaline-earth metal cations, which is due to the higher charge density at
these cations. The characteristics of the complexing ability of N-alkylnitrobenzoaza-15-crown-5 toward alkaline earth metal cations are comparable with analogous characteristics of nitrobenzo-15-crown-5
and are much better than those of N-(4-nitrophenyl)aza-15-crown-5. 相似文献
9.
K. Ikeda M. Yasuda M. Ishikawa K. Esumi K. Meguro W. Binana-Limbele R. Zana 《Colloid and polymer science》1989,267(9):825-830
The physicochemical properties of the, - type (bolaform) surfactant, eicosane-1, 20-bis(triethylammonium bromide) (C20Et6), in aqueous solution have been investigated by means of surface tension, electrical conductivity, dye solubilization, and time-resolved fluorescence quenching (determination of average micelle aggregation number). Using electrical conductivity, the critical micelle concentration of C20Et6 was found to be 6.0×10–3 mol dm–3 and the ionization degree of C20Et6 micelle was found to be 0.42. From surface tension measurments, the molecular area of C20Et6 at the air-water interface was about twice that of normal type surfactants such as dodecyltrimethylammonium bromide (DTAB). The solubilizing power of micellar solution of C20Et6 toward Orange OT was 1.0×10–2 mole of dye per mole of surfactant, i. e., slightly smaller than that of DTAB. The micelle aggregation number,N, was found to be 17±2 by time-resolved fluorescence quenching. C20Et6 showed a very small temperature dependence ofN, much less than for normal surfactants. 相似文献
10.
Djuran Miloš I. Dimitrijević Dejana P. Milinković Snežana U. Bugarčić Živadin D. 《Transition Metal Chemistry》2002,27(2):155-158
The reactions between two monofunctional platinum complexes [Pt(Me4dien)Cl]+ (Me4dien = 1,1,7,7-tetramethyl-diethylenetriamine) and [Pt(Et4dien)Cl]+ (Et4dien = 1,1,7,7-tetraethyldiethylenetriamine) and the peptides, N-acetylated L-methionyl-L-histidine (MeCO–Met–His) and glutathione (GSH), have been investigated by 1H-n.m.r. spectroscopy and u.v.–vis. spectrophotometry. The reactions of the platinum(II) complexes with MeCO–Met–His were carried out at room temperature and at pH 3.0 and 7.0, whereas with GSH the reactions were studied only at pH 3.0. No binding of these two platinum complexes to the sulfur atom of methionine or to nitrogen atoms of histidine residue of MeCO–Met–His was observed during the first 24 h. When the reaction was followed further, after 24 h very slow binding of [Pt(Me4dien)Cl]+ to the N3 nitrogen atom of imidazole was observed. Both platinum complexes react with the sulfur atom of the cysteine residue in GSH. Kinetic data show that GSH reacts twice as fast with [Pt(Me4dien)Cl]+ than with [Pt(Et4dien)Cl]+. Our findings indicate that sterically crowded platinum(II) complexes are only capable of reacting with the sulfhydryl group of the cysteine residue. This influences the design of new platinum(II) complexes for selective covalent modification of peptides and proteins. 相似文献
11.
The resol polycondensation ofC-phenylcalix[4]resorcinarene with formaldehyde affords a corss-linked polymer possessing ion-exchange ability. The ion-exchange
capacity of the polymer with respect to NH4
+, Me4N+, Et4N+, Bu4N+, and K+ cations was determined. The equilibrium in the systemsC-phenylcalix[4]resorcinarene-based polymer—binary or ternary aqueous solutions of electrolytes was studied by potentiometric
titration and quantumchemical MNDO/PM3 calculation
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1475–1477, August, 2000. 相似文献
12.
Genivaldo Julio Perptuo Jan Janczak 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):o709-o711
Crystals of the title salt, [(C6H5NH3)]+·[(HOOC(CH2)CH(OH)COO)]− or C6H8N+·C4H5O5−, are built up from protonated anilinium residues and monodissociated dl ‐malate ions. The NH3+ group of the anilinium cation is ordered at room temperature. Rotation of the NH3+ group along the C(aromatic)—Nsp3 bond (often observed at room temperature in other anilinium salts) is prevented by N—H⋯O hydrogen bonds between the NH3+ group and the malate anions. The anions are connected by four O—H⋯O hydrogen bonds into two‐dimensional sheets parallel to the (001) plane. The charged moieties, i.e. the anilinium cations and the sheets of hydrogen‐bonded malate anions, form two‐dimensional layers in which the phenyl rings of the anilinium residues lie perpendicular to the malate‐ion sheets. The conformation of the monodissociated malate ion in the crystal is compared with that obtained from ab initio molecular‐orbital calculations. 相似文献
13.
IntroductionImidazolehasattractedconsiderableinterestasalig andinmanybiologicalsystemsinwhichitprovidesapo tentialbindingsiteformetalions .1Imidazoleitselfisanunidentateligandandformscomplexeswithmetalionsthroughitstertiarynitrogenatom .Somecomplexesofi… 相似文献
14.
Juan Server-Carrió Emilio Escrivà José-Vicente Folgado 《Transition Metal Chemistry》1996,21(6):541-545
Summary The crystal and molecular structure of [Cu(Im)6] (HCOO)2 (Im = imidazole) has been determined by X-ray diffraction methods. The compound is built of centrosymmetric Cu(Im)
inf6
sup2–
cations and non-coordinated HCO2
– anions, linked through H-bonds giving a layered structure in the ac plane. The coordination polyhedron around the Cu atoms can be described as a rhombically-distorted octahedron (CuN2N2N'2 chromophores). Both electronic and e.p.r. spectra are indicative of an essentially d
x2–
y2
ground state for the CuII ions. No exchange coupling has been detected down to 4.2 K by means of magnetic susceptibility measurements. This feature is discussed on the basis of the structural data. 相似文献
15.
Yasuyuki Irie Kensuke Naka 《Journal of polymer science. Part A, Polymer chemistry》2013,51(12):2695-2701
An imidazole‐terminated hyperbranched polymer with octafunctional POSS branching units denoted as POSS‐HYPAM‐Im was prepared by the polymerization of excess amounts of tris(2‐aminoethyl)amine with the first‐generation methyl ester‐terminated POSS‐core poly(amidoamine)‐typed dendrimer, reacting with methyl acrylate, and ester‐amide exchange reaction with 3‐aminopropylimidazole. The imidazole‐terminated hyperbranched poly(amidoamine) denoted as HYPAM‐Im was also synthesized with 1‐(3‐aminopropyl)imidazole from a methyl ester‐terminated hyperbranched poly(amidoamine) by the ester‐amide exchange reaction. The transmittance of the POSS‐HYPAM‐Im solution drastically decreased when the solution pH was greater than 8.2. On the other hand, the transmittance of the HYPAM‐Im solution gradually decreased when the solution pH at 8.5 and was greater than 9. Spectrophotometric titrations of the hyperbranched polymer aqueous solutions with Cu2+ ions indicated the variation of the coordination modes of POSS‐HYPAM‐Im from the Cu2+–N4 complex to the Cu2+–N2O2 complex and the existence of the only one complexation mode of Cu2+–N4 between Cu2+ ion and HYPAM‐Im with increasing the concentrations. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2695–2701 相似文献
16.
Rate constants and activation parameters for the isotopic exchange reactions between (PhO)2PSCl and M36Cl (M = Me4N+, Et4N+, n-Bu4N+, Et3HN+, EtH3N+, Li+) in acetonitrile were measured in order to find the effect of the cation nature onthe kinetics of the reaction. The rate constants measured for a range of concentrations of Et3HN36Cl, EtH3N36Cl, and Li36Cl were analyzed using the Acree equation. The equivalent conductance of LiCl in acetonitrile was determined. The nature of the cation has no effect on the mechanism of the reaction. The cation changes only the experimental rate constant proportionally to the dissociation degree of the salt. Smaller values of the rate constant and smaller activation parameters ΔH? and ΔS? for the reaction with Li36Cl indicate the existenceof the intermolecular interaction between lithium ions and O,O-diphenylphosphorochloridothionate. 相似文献
17.
Slocik Joseph M. Ward Matthew S. Somayajula Kasi V. Shepherd Rex E. 《Transition Metal Chemistry》2001,26(3):351-364
The 'caged NO' reagent, RuCl3NO(H2O)2, has been studied by n.m.r. and i.r. methods with imidazole, histidine, histamine, and N-methyliminodiacetate as complexing ligands. These ligands are representative of cellular donors that would be encountered as RuCl3NO(H2O)2 migrates through biological cells. [RuCl3NO(imH)(H2O)], [RuCl3(NO)(imH)2] and [RuCl2(NO)(imH)3]+ complexes (imH = imidazole) have been detected by 1H-n.m.r. and i.r. and electrospray mass spectrometry (e.s.i.–m.s.) methods. Based upon the effect of cis ligand addition on the (NO) frequency causing a decrease in frequency, the 1:1 and 1:2 complexes have the imidazole donors in the plane cis to the NO+ moiety, whereas the 1:3 species has the third imidazole trans to the NO+. The trans imidazole donor causes 'trans-strengthening' of the N–O bond of the {RuNO}6 chromophore. 1H-n.m.r. shows that the monodentate imidazole donor(s) is (are) in rapid exchange with free imidazole in solution for each of the n = 1–3 species. Histidine and histamine make kinetically more stable 1:1 complexes with the major isomer having an axially-coordinated histidine imidazole donor, but in-plane donation for histamine. The carboxylate of coordinated histidine remains pendant according to i.r. and 13C-n.m.r. data. From syntheses carried out at pH ca. 5, the amino donor is H-bonded to an in-plane H2O in the major species (ca. 75%) and coordinated with displacement of the in-plane H2O in the lesser isomer (25%). By contrast, the histamine ligand binds with an in-plane bound imidazole and a pendant protonated amino group (94%). The remaining 6% has an in-plane chelated histamine, analogous to the bis imidazole species and the known fac, cis-[RuCl3NO(en)] complex. N-Methyliminodiacetate is observed to form one main [RuCl(NO)(mida)(H2O)] complex (85%) with two chelated glycinato donor groups with RuCl3NO(H2O)2, one glycinato group chelated 'in-plane' with the central amine donor and one axial coordinated glycinato donor. A second [RuCl(NO)(mida)(H2O)] complex (the remaining 15%) has the amine donor trans to NO+ and chelated glycinato groups which coordinate in the RuClO2(OH2) plane, either cis or trans to each other, in a 60:40 split (ca. 9% and 6%). The presence of one Cl– and one H2O in the [RuCl(NO)(mida)(H2O)] complexes was established by e.s.i.–m.s. These results show that RuCl3NO(H2O)2 is likely to be freely mobile within a cellular environment, forming stable complexes via bidentate chelation with 'two-point' nitrogen donors (en, his, etc). 相似文献
18.
Viktor Kettmann Jan Lokaj Viktor Milata Jozef Salo Mohamed Mahmoud Mohamed Hasan 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o365-o366
The title compound, C11H10N3+·Cl?·H2O, belongs to the N1‐methyl‐substituted imidazo[4,5‐f]quinoline family, in which the heterocyclic ring is protonated at the pyridine rather than at the imidazole N atom. The molecule as a whole is almost exactly planar. The molecular structure has been compared with that of the 2‐amino analogue described in the literature, and it was found that the extra amino group of the latter is involved in conjugation with the adjacent double bond, i.e. the conjugation does not extend over the entire heterocyclic system. The cation of the title compound forms a strong hydrogen bond with the Cl? anion and the anions are interconnected by the water solvent molecule. 相似文献
19.
Synthesis and Ligand Modification Chemistry of a Molybdenum Dinitrogen Complex: Redox and Chemical Activity of a Bis(imino)pyridine Ligand
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Grant W. Margulieux Zoë R. Turner Prof. Paul J. Chirik 《Angewandte Chemie (International ed. in English)》2014,53(51):14211-14215
The bis(imino)pyridine 2,6‐(2,6‐iPr2‐C6H3N?CPh)2‐C5H3N (iPrBPDI) molybdenum dinitrogen complex, [{(iPrBPDI)Mo(N2)}2(μ2,η1,η1‐N2)] has been prepared and contains both weakly (terminal) and modestly (bridging) activated N2 ligands. Addition of ammonia resulted in sequential N? H bond activations, thus forming bridging parent imido (μ‐NH) ligands with concomitant reduction of one of the imines of the supporting chelate. Using primary and secondary amines, model intermediates have been isolated that highlight the role of metal–ligand cooperativity in NH3 oxidation. 相似文献
20.
Jie Han Dr. Shuang‐Quan Zang Dr. Thomas C. W. Mak Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(17):5078-5088
A series of five complexes that incorporate the guanidinium ion and various deprotonated forms of Kemp’s triacid (H3KTA) have been synthesized and characterized by single‐crystal X‐ray analysis. The complex [C(NH2)3+] ? [H2KTA?] ( 1 ) exhibits a sinusoidal layer structure with a centrosymmetric pseudo‐rosette motif composed of two ion pairs. The fully deprotonated Kemp’s triacid moiety in 3 [C(NH2)3+] ? [KTA3?] ( 2 ) forms a record number of eighteen acceptor hydrogen bonds, thus leading to a closely knit three‐dimensional network. The KTA3? anion adopts an uncommon twist conformation in [(CH3)4N+] ? 2 [C(NH2)3+] ? [KTA3?] ? 2 H2O ( 3 ). The crystal structure of [(nC3H7)4N+] ? 2 [C(NH2)3+] ? [KTA3?] ( 4 ) features a tetrahedral aggregate of four guanidinium ions stabilized by an outer shell that comprises six equatorial carboxylate groups that belong to separate [KTA3?] anions. In 3 [(C2H5)4N+] ? 20 [C(NH2)3+] ? 11 [HKTA2?] ? [H2KTA?] ? 17 H2O ( 5 ), an even larger centrosymmetric inner core composed of eight guanidinium ions and six bridging water molecules is enclosed by a crust composed of eighteen axial carboxyl/carboxylate groups from six HKTA2? anions. 相似文献