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1.
José S. Casas Eduardo E. Castellano Javier Ellena María S. García-Tasende Agustín Sánchez José Sordo Monica Toma 《Polyhedron》2008
The reaction of dimethylthallium(III) hydroxide with picolinic acid (Hpic), 3-hydroxypicolinic acid (H23hpic) and 6-hydroxypicolinic acid (H26hpic) in an aqueous/methanol mixture afforded the complexes [TlMe2(pic)] (1), [TlMe2(H3hpic)] (2) and [TlMe2(H6hpic)] (3), respectively. Complex 3′, [NaTlMe2(6hpic)2]n, was obtained as a minor product from a methanolic solution of 3. Compounds 1–3 were characterized by IR and Raman spectroscopy and, in the cases of 1, 2 and 3′, by single-crystal X-ray diffraction. Complex 3′ is the first example of an H6hpic− heterobimetallic compound to be isolated. The 1H and 13C NMR spectra of 1 and 2 are also discussed. 相似文献
2.
The 14N nuclear quadrupole resonance (NQR) quadrupole coupling tensors of picolinic, nicotinic, isonicotinic and dinicotinic acids have been determined. Two different 14N quadrupole coupling constants 1007 kHz and 4159 kHz have been observed for picolinic acid demonstrating the presence of both protonated and non-protonated nitrogen atoms in this system in the solid. Only one set of non-protonated 14N NQR lines has been observed in other pyridinecarboxylic acids demonstrating the absence of the protonated zwitter ion forms observed in picolinic acid. The non-protonated 14N quadrupole coupling constant is the highest for the non-protonated nitrogen in picolinic acid and decreases to 3774 kHz in nicotinic acid and 3570 kHz in isonicotinic acid. It is the lowest in dinicotinic acid where the corresponding 14N quadrupole coupling constant is 2794 kHz. The observed anomalous decrease in the 14N quadrupole coupling constant of dinicotinic acid with decreasing temperature is tentatively explained as reflecting the increase in the residence time of the N–H?O bonded proton in the potential well close to the nitrogen. 相似文献
3.
E. Kemnitz U. Groß St. Rüdiger G. Scholz D. Heidemann S.I. Troyanov I.V. Morosov M.-H. Leme-Cailleau 《Solid State Sciences》2006,8(12):1443-1452
To get some insight by conclusions of analogy into the drying process of alcoholic aluminium fluoride sol–gels [AlF3/(ROH)x], the structures of α- and β-AlF33H2O as well as of the nonahydrate AlF39H2O are reinvestigated and discussed based on X-ray single crystal structural data. In addition, neutron diffraction experiments of the latter allowed the refinement of proton positions. In accordance with crystal structures, low-temperature solid state 27Al-, 1H- and 19F-MAS NMR spectra convincingly confirm the structural similarity between α-AlF33H2O and AlF39H2O, while the β-phase material is structurally different forming chain structures. Thermal analysis of AlF3/(ROH)x gave evidence for discrete AlF3:ROH ratios of only 1:0.45 and 1:0.1, and solution NMR showed some similarities between aqueous and alcoholic systems. 相似文献
4.
Tristram Chivers Cees Lensink John F. Richardson 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):189-192
Abstract The preparation and X-ray structure (M=Mo) of complexes of the type M(CO)5(Ph2PNSO) (M=Cr,Mo) are described. These complexes are used in the synthesis of homo- and hetero-dinuclear complexes of Ph2PNSNPPh2. A 31P DNMR study of these dinuclear complexes indicates a cis, trans → trans, cis isomerization in solution. The preparation and X-ray structure (M=Cr) of the mononuclear complexes, cis-M(CO)4(P(Ph)2NSN(Ph)2P), (M=Cr,Mo) are also described. 相似文献
5.
P. Koczoń J.Cz. Dobrowolski W. Lewandowski A.P. Mazurek 《Journal of Molecular Structure》2003,655(1):89-95
The experimental and theoretical (B3PW91/6-311++G**) vibrational (IR and Raman) spectra of picolinic, nicotinic and isonicotinic acids (pyridine-2-, -3-, and -4-carboxylic acid, respectively) were studied. Three stable calculated structures were found for picolinic acid: the structure with intramolecular hydrogen COOH?N bond, and the two without hydrogen bond. For the nicotinic acid two stable theoretical structures differ in orientation of the COOH group with respect to the nitrogen atom, whereas for the isonicotinic acid only one form was stable. The theoretical vibrational spectra of the three acids were interpreted by means of potential energy distributions (PEDs) using VEDA 3 program. Next, selected experimental bands were assigned based on the scaled theoretical wavenumbers. Finally, the wavenumbers and intensities for the three isomeric acids were compared and discussed in terms of location of the carboxylic group. 相似文献
6.
《Journal of Coordination Chemistry》2012,65(1):109-115
The structure of a mononuclear Au(III) complex of the dipeptide glycyl-S-serine (Gly-Ser) has been predicted using solid-state linear dichroic IR (IR-LD) spectroscopy, based on an orientation technique in a nematic liquid crystal suspension. Results are compared with data from 1H- and 13C-NMR, MS, elemental analysis, thermogravimetry and differential scanning calorimetry. The metal ion is coordinated as a tridentate through NH2, N (from deprotonated amide) and O (COO?) groups to form [Au(C5H9N2O4)Cl], with the fourth position of the square-planar coordination sphere being completed by a Cl? ion. 相似文献
7.
Toma? Skapin Zoran Mazej Adolf Jesih Sven L.M. Schroeder Norbert Weiher John M. Winfield 《Journal of fluorine chemistry》2011,132(10):703-712
Decomposition of hydrazinium pentafluoroaluminate under oxidative (F2) conditions leads to aluminium(III) fluoride whose properties are highly dependent on the conditions used for synthesis. In the presence of anhydrous HF, which probably acts as a heat exchange agent, samples have high BET areas, whereas BET areas of samples prepared under gas-solid conditions are small. XPS data are consistent with the presence of Lewis acid centres but, more importantly, emphasise the importance of surface hydroxyl groups, particularly in high surface area compounds. Catalytic behaviour towards isomerisation of 1,1,2-trichlorotrifluoroethane and subsequent dismutations at moderate temperatures and towards room temperature dehydrochlorination of tert-butyl chloride has been demonstrated for some high BET samples; both reactions indicate that surface Lewis sites exist. Catalytic ability is inhibited by surface hydroxyl groups but is improved by prior fluorination of the surface with CCl2F2. Catalysis is inhibited also by the presence of ammonium fluoroaluminate, a by-product of the decomposition process. The [NH4]+ salt level can be reduced by washing with anhydrous HF. 相似文献
8.
A spectrofluorimetric method is reported for the determination of Al(III), based on the formation of a fluorescent Al(III)-Eriochrome Red B complex in the presence of hexamethylenetetramine at 60°C. Fluorescence measurements were made at 2°C and all variables that affect the development of the complex are reported. The method is very selective and the detection limit is 0.1 ng ml?1. It was applied to the determination of Al(III) in tap water. 相似文献
9.
Anna Wojciechowska Lechosław Łomozik Stanisław Zieliński 《Monatshefte für Chemie / Chemical Monthly》1987,118(12):1317-1324
The composition and stability of La3+, Pr3+ and Lu3+ complexes with aspartic acid and asparagine were analysed. The formation of complexes of the typeML andMHL was determined for La3+ and Pr3+ with aspartic acid, and of the typeMHL for Lu3+ with aspartic acid. For La3+, Pr3+ and Lu3+ with asparagine the formation ofML(OH) complexes was observed. By means of1H NMR and13C NMR studies the participation in the coordination of both -COOH groups was determined for aspartic acid, whereas for asparagine the participation of the -COOH group was determined in complexes with La3+, Pr3+, and of the -COOH and the -NH2 groups in the complex with Lu3+.
Potentiometrische und spektroskopische Untersuchungen an La(III), Pr(III) und Lu(III)-Komplexen von Asparaginsäure und Asparagin
Zusammenfassung Die Zusammensetzung und die Stabilität von La3+, Pr3+ und Lu3+-Komplexen mit Asparaginsäure und Asparagin wurden untersucht. Es wurde die Bildung von La3+ und Pr3+-Komplexen des TypsML undMHL, und ein Lu3+-Komplex des TypsMHL mit Asparaginsäure festgestellt. Für diese drei Lanthaniden wurde auch die Bildung von Komplexen des TypsML(OH) mit Asparagin beobachtet. Mit Hilfe von1H-NMR und13C-NMR-Untersuchungen wurde für Asparaginsäure die Teilnahme der beiden -COOH-Gruppen, für Asparagin die Teilnahme der -COOH-Gruppe in den Komplexen mit La3+, Pr3+ und der-COOH und -NH2-Gruppen in dem Komplex mit Lu3+ an der Koordinierung festgestellt.相似文献
10.
Complexation of aluminium(III) with the fluorogenic ligand chromotropic acid (4,5-dihydroxynaphthalene-2,7-disulfonic acid) has been revisited with the aim of using enhancement of the fluorescence intensity as an analytical tool. Complexation at the optimum pH4 was shown to lead to a 1:1 complex with a stability constant log
110=18.4±0.7. The fluorogenic effect was thoroughly investigated. Nearly selective excitation of the chelate rather than the ligand could be achieved at wavelengths longer than 360 nm. For analytical purposes the main interfering ion was Ga3+. The strongest competing ligand was shown to be citric acid. Competitive complexation by acetate or formate ions can also make their use in a buffer at the usual concentration, 0.2 mol L–1, questionable, whereas a 10–2 mol L–1 formic acid buffer was shown to be a good alternative. The calibration plot showed that the dependence of response on Al(III) concentration was linear up to 500 g L–1; the detection limit was 0.65 g L–1 (3SD
blank, n=10, SD=±1.4% at 10 g L–1 and ±0.8% at 100 g L–1). The analytical procedure was successfully applied to several samples of tap water and the results were in good agreement with those from AAS determination. 相似文献
11.
12.
The complexation of Al(III) with d-gluconic acid was studied in solution by means of pH-potentiometry, ESI mass spectrometry and one- and two-dimensional NMR spectroscopy. Six complexes were found to form in solution from pH 2 to 10: [AlL]2+, [AlLH−1]+, [AlLH−2], [AlLH−3]−, [AlL2H−1] and [AlL2H−2]−. NMR spectroscopy indicated very complicated chemical exchange processes between the free ligand and gluconic acid molecules bound in the metal complexes, with different coordination modes resulting in changes both of the chemical shift and of the line shape of the signals. A solid complex [AlL2H−1] · 2H2O was isolated as a microcrystalline powder and characterized. The structures of the complexes are discussed on the basis of the spectroscopic results and MM force field calculations. 相似文献
13.
M. A. M. Khouna M. T. Ben Dhia M. R. Khaddar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1673-1682
The two octahedral complexes SnCl4·2(O)PF(NR2)2 (R = Me or Et) were prepared from reaction of SnCl4 with the ligand (R2N)2P(O)F in anhydrous CHCl3. The new adducts have been characterized by elemental analysis, IR, and multinuclear (119Sn, 31P, 19F, and 1H) NMR spectroscopy. The NMR data show that the adducts exist in solution as a mixture of cis and trans isomers with markedly different proportions. When compared with previously described hexamethylphosphoramide (HMPA) and trimethylphosphate (TMPA) analogues, our results indicate that the cis isomer is the predominant species in solution. Low temperature 31P and 119Sn NMR spectra show that the compounds partially dissociate in dichloromethane. 相似文献
14.
M. T. Ben Dhia M. A. M. K. Sanhoury C. Zenati M. R. Khaddar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):3082-3089
The complexes CdL4(ClO4)2 (1), CdL2(NO3)2 (2), and CdL2Cl2 (3) (L = (Me2N)3P(Se)) have been prepared and characterized by elemental analysis, conductivity measurements, IR, and multinuclear (31P, 77Se, and 113Cd) NMR spectroscopy. 31P and 77Se NMR data were informative of changes associated with complex formation. The structure of the prepared complexes was further confirmed in solution by their 113Cd NMR spectra, which show a quintuplet for the perchlorate complex and a triplet for each of the nitrate and chloride complexes due, respectively, to coupling with four and two equivalent phosphorus atoms, consistent with a four coordinate tetrahedral geometry for the cadmium center. The NMR data are discussed and compared with those reported for related complexes. 相似文献
15.
《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2309-2317
Complexes of beryllium chloride and nitrate with (Me2N)2P(O)F were characterized in solution by multinuclear NMR spectroscopy and in some cases by IR spectroscopy and conductimetry. 31P and 19F NMR spectra were informative of changes associated with complex formation revealing resonances consistent with different species in solution and suggest an equilibrium between these species in both beryllium derivatives. These compounds show narrow lines in the solution 9Be NMR spectra, indicative of a highly symmetric environment for beryllium. The presence of the different species was more pronounced in beryllium chloride complexes. The results are compared to those reported in the literature for hexamethylphosphoramide (HMPA). 相似文献
16.
The synthesis and luminescence of four new iridium (III) diazine complexes (1-4) were investigated. HOMO and LUMO energy levels of the complexes were estimated according to the electrochemical performance and the UV-Vis absorption spectra, showing the pyrimidine complexes have a larger increase for the LUMO than the HOMO orbital in comparison with the pyrazine complexes. Several high-efficiency yellow and green OLEDs based on phosphorescent iridium (III) diazine complexes were obtained. The devices emitting yellow light based on 1 with turn-on voltage of 4.1 V exhibited an external quantum efficiency of 13.2% (power efficiency 20.3 lm/W), a maximum current efficiency of 37.3 cd/A. The electroluminescent performance for the green iridium pyrimidine complex of 3 is comparable to that of the iridium pyridine complex (PPY)2Ir(acac) (PPY = 2-phenylpyridine), which is among the best reported. 相似文献
17.
Mahmood Nickkho-Amiry Gehan Eltanany Stefan Wuttke Stephan Rüdiger Erhard Kemnitz John M. Winfield 《Journal of fluorine chemistry》2008,129(5):366-375
The behaviour of the sol–gel prepared, amorphous solids, high surface area (HS) aluminium fluoride and magnesium fluoride in promoting room temperature dehydrochlorination of tert-butyl chloride (ButCl), in their catalytic activity for the dismutation of chlorodifluoromethane and in the temperature programmed desorption of ammonia is similar, indicating that, unexpectedly, both solids exhibit significant surface Lewis acidity. Using a similar approach, it has been demonstrated that surface Lewis acidity in HS-MgF2 is enhanced by the incorporation of amorphous iron(III) fluoride and probably also by amorphous aluminium(III) fluoride. A second, unexpected feature is the substantial retention of anhydrous hydrogen chloride by all the solids, which is observed by the use of chlorine-36 labelling, when they are exposed at room temperature either to ButCl or to HCl directly. The detailed behaviour of H36Cl towards HS-AlF3 depends on the fluorinating agent, dichlorodifluoromethane or anhydrous hydrogen fluoride, which is used in the second stage of HS-AlF3 synthesis. This observation and the pattern of the results obtained overall lead to the proposal that strongly adsorbed HCl behaves as an unconventional Lewis base towards these solids. 相似文献
18.
H. P. S. Chauhan Jaswant Carpenter Sumit Bhatiya Abhilasha Bakshi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):1713-1722
Abstract Replacement reactions of bis(diethyldithiocarbamato)antimony(III) chloride have been carried out with oxygen and sulfur donor ligands such as disodium oxalate, sodium acetate, sodium salicylate, benzoic acid, thioglycolic acid, acetylacetone, thiphenol, ethane-1,2-dithiol, and 2,2-dimethylpropane-1,3-diol to give mixed bis(diethyldithiocarbamato)antimony(III) derivatives of the corresponding ligands. These derivatives have been characterized by the physicochemical [melting point and molecular weight determination, elemental analysis (C, H, N, S, and Sb)], spectral [FT-IR, far-IR, NMR (1H and 13C)], ESI-mass, powder XRD, and SEM studies. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables] 相似文献
19.
The ‘formal’ hydrolysis ratio (h = C(OH−)added/C(Al)total) of hydrolysed aluminium-ions is an important parameter required for the exhaustive and quantitative speciation-fractionation of aluminium in aqueous solutions. This paper describes a potentiometric method for determination of the formal hydrolysis ratio based on an automated alkaline titration procedure. The method uses the point of precipitation of aluminium hydroxide as a reference (h = 3.0) in order to calculate the initial formal hydrolysis ratio of hydrolysed aluminium-ion solutions. Several solutions of pure hydrolytic species including aluminium monomers (AlCl3), Al13 polynuclear cluster ([Al13O4(OH)24(H2O)12]7+), Al30 polynuclear cluster ([Al30O8(OH)56(H2O)26]18+) and a suspension of nanoparticulate aluminium hydroxide have been used as ‘reference standards’ to validate the proposed potentiometric method. Other important variables in the potentiometric determination of the hydrolysis ratio have also been optimised including the concentration of aluminium and the type and strength of alkali (Trizma-base, NH3, NaHCO3, Na2CO3 and KOH). The results of the potentiometric analysis have been cross-verified by quantitative 27Al solution nuclear magnetic resonance (27Al NMR) measurements. The ‘formal’ hydrolysis ratio of a commercial basic aluminium chloride has been measured as an example of a practical application of the developed technique. 相似文献
20.
Fatma S.M. Hassan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):406-417
Complexes of the type [Pt R2 (dppma-PP′)] (R─Me, Et, Ph, CH2Ph, C6H4 Me-p, C6H4OMe-2, CH2CMe3, 1-naphthyl, C6H4Me-o, dppma = Ph2PNMe PPh2) have been prepared from [PtCl2, (dppma-PP′)] and the corresponding alkyl-lithium or Grignard reagents. Equilibrium constants, k, for the conversion of [PtR2 (dppma-PP′)] into cis-[PtR2(dppma-P)2] with dppma were studied using 31P NMR spectroscopy at room temperature. Equilibrium is rapidly established for R─C6H4-Me-o, at 20°C. Complex of the type cis-[PtR2 (dppma-P)2] was isolated R─C6H4 Me-o. The complexes [PtMe2(dppma-P)2] and [Pt(o-methoxyphenyl)2(dppma-P)2] were prepared, but unfortunately decomposed once isolated, the only evidence for its formation being from 31P-{1H} NMZR spectroscopy. The o-tolyl or 1-naphthyl complexes exist as syn-anti mixtures in solution, due to restricted rotation around the platinum aryl bonds. Treatment of several complexes of the type [PtR2(dppma-PP′)] with MeI gives [PtR2Me(I)(dppma-PP′)] with trans addition of MeI. Treatment of [PtR2(dppma-PP′)] with HCl gives [Pt Cl (R) (dppma-PP′)] for R─C6H2Me3-2,4,6, C6H4-CH3-2, C6H4-Me-4, Me, 1-naphthyl. The 1H, 31P NMR parameters for these complexes are discussed. Attempted preparation of complexes of the type [PtR2 (dppma-P)2M] (R─C6H4-Me-2, Me CN-C6H4-Me-4); M─Pd, Pt, Au,) are reported. 相似文献