Structural characterization, thermal, dielectric, vibrational properties and molecular motions in

[C₃N₂H₅]₆[Bi₄Br₁₈] has been synthesized and characterized by the X-ray (at 293 and 110 K), calorimetric, dilatometric and dielectric measurements. At room temperature it crystallizes in the monoclinic space group, C2/m. A crystal structure consists of disordered imidazolium cations and ordered discrete tetramers of [Bi₄Br₁₈]^6-. This compound reveals a rich polymorphism in a solid state. It undergoes three solid–solid phase transitions: from phase I to II at 426/423 K (heating–cooling), II→III at 227 K and III→IV at 219.5/219 K. A clear dielectric relaxation process is found in the room temperature phase II. Infrared studies of the polycrystalline [C₃N₂H₅]₆[Bi₄Br₁₈] showed that the ν(N–H), δ(ring) and δ(C–H) modes of the imidazolium cations appeared to be very sensitive to the IV→III phase transition. ¹H NMR measurements confirmed a key role of the imidazolium cations in the phase transitions mechanisms at low temperatures.     

Temperature dependence of121Sb nuclear quadrupole resonance frequencies in the spectra of M2Sb2SO4F6 (M = K,Rb, NH4)

The temperature dependence of the frequencies of¹²¹Sb nuclear quadrupole resonance in the spectra of M₂Sb₂SO₄F₆ (M = K, Rb, NH₄) was studied in the temperature range from 77 to 340 K. A secondary phase transition was found above 320 K for (NH₄)₂SO₄F₆.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1831–1833, October, 1994.This study was sponsored by the Russian Foundation for Basic Research (Grant No. 93-03-4394).     

Potentiometric and spectral studies of complex formation of La(III), Pr(III) and Lu(III) with aspartic acid and asparagine

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⁺.

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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.

     

Manifestation of electron-nuclear motions in the123Sb NQR spectra of pentafluoroantimonites

A dependence between the quadrupole coupling constants (e ² Qq _zz ) and the asymmetry parameters of the electric field gradient (η) for the antimony atoms in the complex [SbF₅]²⁻ anions of M₂SbF₅ pentafluoroantimonites (M=Na, K, Rb, Cs, NH₄, Ti, and Et₂NH₂) was revealed from the¹²³Sb NQR spectra at 77 K. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1988–1990, October, 1998.     

An Au(III) complex of glycyl- S -serine: a linear polarized IR and 1H- and 13C-NMR investigation

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.     

121,123Sb NQR investigation of chlorofluoroantimonates(III) M2SbCl3F2 (M = Rb. Cs,and NH4)

Antimony(m) chlorofluoride complexes M₂SbCl₃F₂ (M = Rb, Cs, or NH₄) were studied by the^121,123Sb NQR method. A temperature range (77–285 K) with anomalous change in the NQR parameters and a second-order phase transition at 250–280 K for (NH₄)₂SbCl₃F₂ were found.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 382–385, February, 1996     

209Bi NQR study of bismuth(III) complexes

Potassium pentafluorobismuthate(III), nitrate-chloride Bi^III complexes MBiCl₃NO₃ (M=K, (NH₂)₂CNH₂), sulfate-chloride Bi^III complexes MBiCl₂SO₄ (M=K, Rb, NH₄, (NH₂(₂CNH₂), and Bi^III complexonates with the anions of ethylenediaminetetraacetic acid M[Bi(edta)]₂·nH₂O (M=Mg, Ca, Ni, Cd) and nitrilotriacetic acid Bi(nta)·2H₂O, and Bi(nta)·3thio·H₂O (thio is thiourea) were studied by²⁰⁹Bi NQR spectroscopy. A second-order phase transition was observed in K₂BiF₅ at 100 K. The compounds Bi(nta)·2H₂O, (NH₂)₂CNH₂BiCl₃NO₃, and MBiCl₂SO₄ (M=K, NH₄) are piezoelectrics. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2237–2240, November, 1998.     

Coordination behaviour of the multidentate Schiff base 2,6-bis(2-hydroxyphenyliminomethyl)pyridine towards the fac-[Re(CO)3] and [ReO] cores

The seven-coordinate rhenium(III) complex cation [Re^III(dhp)(PPh₃)₂]⁺ was isolated as the iodide salt from the reaction of cis-[Re^vO₂I(PPh₃)₂] with 2,6-bis(2-hydroxyphenyliminomethyl)pyridine (H₂dhp) in ethanol. In the complex fac-[Re(CO)₃(H₂dhp)Br], prepared from [Re(CO)₅Br] and H₂dhp in toluene, the H₂dhp ligand acts as a neutral bidentate N,N-donor chelate. The complexes were characterized by elemental analysis, infrared and ¹H NMR spectroscopy and X-ray crystallography.     

Cerium(III) Complexes with Lacunary Polyoxotungstates. Synthesis and Structural Characterization of a Novel Heteropolyoxotungstate Based on α-[SbW9O33]9− Units

Several cerium(III) complexes with lacunary polyoxotungstates -B-XW₉O^9– ₃₃ (X=As^III, Sb^III) and W₅O^6– ₁₈, have been synthesized and characterized by single-crystal X-ray analysis, elemental analysis and IR spectroscopy. The X-ray analysis of Na₂₅[Ce(H₂O)₅As₄W₄₀O₁₄₀]63H₂O (1) reveals the framework of the well-known [As₄W₄₀O₁₄₀]^28– anion with a {Ce(H₂O)₅}³⁺ unit in the central site S1. The anion in (NH₄)₁₉[(SbW₉O₃₃)₄{WO₂(H₂O)}₂Ce₃(H₂O)₈(Sb₄O₄)]48H₂O (2) consists of a tetrahedral assembly of four -B-Sb^IIIW₉O^9– ₃₃ units connected by two additional six-coordinate tungsten atoms, three nine-coordinate monocapped square-antiprismatic cerium atoms and a Sb₄O₄ cluster. The Ce^III center in the [Ce(W₅O₁₈)₂]^9– anion in Na₉[Ce(W₅O₁₈)]NaCl30H₂O (3) displays the square-antiprismatic environment observed in all complexes of the type [Ln(W₅O₁₈)₂] ^n–.     

Nuclear magnetic resonance VI. Some quantitative applications of carbon-13 NMR spectroscopy to phenylindoles

Summary The number of carbons represented by each signal of the phenylindoles1,4, and5 is measured quantitatively by integration of their¹³C NMR spectra, recorded after adding chromium(III) acetylacetonate to the sample solutions as a paramagnetic relaxation agent. Their carbon chemical shifts are assigned unambiguously; the literature assignments of4 are confirmed. By a comparative study of the carbon chemical shifts of1,4, and5, those of2 and3 are also assigned. Theortho carbons of the phenyl group of4 resonate upfield with respect to thepara carbon. Theortho carbons of the 2- and 3-phenyl moieties of1–3 and5, however, are found to absorb downfield from the correspondingpara carbons, probably because of steric and/or electronic effects exerted by their neighbouring phenyl group.

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Kernresonanzspektroskopie, 6. Mitt. Einige quantitative Anwendungen der¹³C-NMR-Spektroskopie auf Phenylindole

Zusammenfassung Die Anzahl der durch jedes Signal der Phenylindole1,4 und5 repräsentierten Kohlenstoffatome wird durch Integration der nach Zusatz von Chrom(III)acetonylacetat als Relaxationsreagens aufgenommenen¹³C-NMR-Spektren bestimmt. Ihre chemischen Verschiebungen werden eindeutig zugeordnet; die Literaturwerte für4 werden bestätigt. Durch eine vergleichende Untersuchung der¹³C-chemischen Verschiebungen von1,4 und5 können jene von2 und3 ebenfalls zugeordnet werden. Dieortho-Kohlenstoffe der Phenylgruppe von4 sind gegenüber denpara-Kohlenstoffatomen zu höherem Feld verschoben. Für die 2- und 3-Phenyl-Substituenten von1–3 und5 kehren sich die Verhältnisse um, wahrscheinlich wegen sterischer und/oder elektronischer Effekte der benachbarten Phenylgruppe.

     

Bis(Diethyldithiocarbamato)Antimony(III) Derivatives with Oxygen- and Sulfur-Donor Ligands: Synthesis,Esi-Mass,and Spectral Characterization

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]     

Aluminum Solvate Complexes Forming in Acidic Methanol-Acetone Mixtures Studied by <Superscript>27</Superscript>Al NMR Spectroscopy

²⁷Al NMR spectroscopy is a powerful tool for the study of coordination and solvation in both aqueous and nonaqueous solutions. In this study, the complexes coexisting upon dissolution of AlCl₃ in acidic acetone + methanol solutions are shown to consist essentially of mixed hexacoordinated species of the general formula [Al(CH₃OH)_6−n (CH₃COCH₃) _n ]³⁺ (n=1,2 and 3), all exhibiting distinctly different ²⁷Al shielding effects. The relative populations of the various mixed species are found to be highly dependent upon the acetone:methanol mole ratio that in the more acetone-rich mixtures with aluminum become appreciably coordinated by acetone. The results demonstrate that the key factor for the formation of acetone-containing species in acidic methanolic solutions is having the CH₃COCH₃:CH₃OH mole ratio at 3:1.     

一个新颖的三维异核锑(III)-镨(III)配合物[Sb2-μ4-(EDTA)2Pr(H2O)5]NO3•4H2O的合成、晶体结构及热分解研究

合成了锑-镨与乙二胺四乙酸形成的新颖三维配合物[Sb₂-μ₄-(EDTA)₂Pr(H₂O)₅]NO₃•4H₂O, 用元素分析、红外光谱、热分析及X射线单晶衍射法等进行了组成和结构表征. 结果表明该配合物属正交晶系, 空间群Pnn2; 晶胞参数: a＝1.07031(2) nm, b＝2.30805(4) nm, c＝0.72343(2) nm, V＝1.78711(7) nm³, Z＝2, D_c＝2.202 g/cm³, F(000)＝1164, μ＝2.955 mm^－1, GOF＝1.000, 最终偏离因子R₁＝0.0203, wR₂＝0.0545 [I＞2σ(I)]. 在标题化合物中, 每个镨(III)离子的配位数为9, 与五个水分子中的五个氧原子和四个羧基氧原子配位, 形成三帽三角棱柱空间配位多面体. 锑(III)与EDTA离子中的四个氧原子和两个氮原子配位, 在赤道平面上有一孤对电子. 同时讨论了配合物的热分解过程.     

1H, 13C, 15N NMR and 13C, 15N CPMAS studies of cobalt(III)-chloride-pyridine complexes, spontaneous py → Cl substitution in trans-[Co(py)4Cl2]Cl, and a new synthesis of mer-[Co(py)3Cl3]

trans-[Co(py)₄Cl₂]Cl·6H₂O, mer-[Co(py)₃Cl₃] and mer-[Co(py)₃(CO₃)Cl] were studied by UV-Vis, far-IR and ¹H, ¹³C, ¹⁵N NMR. The formation of Co-N bonds lead to variable in sign and magnitude changes of ¹H NMR chemical shifts, heavily dependent on proton position, coordination sphere geometry and character of auxiliary ligands. ¹³C nuclei were deshielded upon Co(III) coordination, while ¹⁵N NMR studies exhibited ca. 85–110 ppm shielding effects (ca. 15–25 ppm more expressed for nitrogens trans to N than trans to Cl or O). ¹³C and ¹⁵N CPMAS spectra revealed a slight inequivalency of formally identical Co-py bonds in trans-[Co(py)₄Cl₂]Cl·6H₂O and mer-[Co(py)₃Cl₃], suggesting for the latter complex an existence of distortion isomers. In chloroform, a spontaneous trans-[Co(py)₄Cl₂]Cl → mer-[Co(py)₃Cl₃] + py reaction was monitored by ¹H NMR and UV-Vis. This process of py → Cl substitution allowed the design of a more convenient and efficient method of mer-[Co(py)₃Cl₃] preparation.      

NMR studies of molecular motion in tetramethylammonium hydroxide pentahydrate

Polycrystalline (CH₃)₄NOH·5 H₂O (I) and (CH₃)₄NOD·5D₂O (II) have been studied by¹H NMR lineshapes, second moments and spin-lattice relaxation times and by²H NMR lineshapes as a function of temperature. From low temperatures the first motion to occur is reorientation of the internally rigid (CH₃)₄N⁺ ion about a uniqueC ₃ axis (E _ta = 8.37 kJ/mol forI,E _a = 9.00 kJ/mole forII), followed closely by pseudo isotropic reorientation of the whole ion (E _a = 18.10 kJ/mol). Motion of the cage molecules (water and hydroxide ion) occurs at higher temperatures with an apparentE _a = 11.30 kJ/mol. There is some evidence of a phase transition inII but notI in the 220–230 K region.²H NMR lineshapes ofII below 220 K indicate static cage molecules. Some of the²H quadrupole coupling constants derived from these spectra correspond to O·O hydrogen-bond distances which are incompatible with the known room temperature structure ofI. Above the possible transition inII the anisotropic²H lineshapes indicate rapid motion of²H among all possible hydrogen-bond sites via transfer along the bonds and molecular reorientation. This motion persists in the high temperature phase but the lineshape becomes isotropic due to the cubic symmetry of this phase. It is possible that¹H or²H tunnelling plays an important part in the motion of the cage molecules and the different phase behaviour ofI andII.Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena.     

Calcium Sulfite Solids Activated by Iron for Enhancing As(III) Oxidation in Water

Desulfurized gypsum (DG) as a soil modifier imparts it with bulk solid sulfite. The Fe(III)–sulfite process in the liquid phase has shown great potential for the rapid removal of As(III), but the performance and mechanism of this process using DG as a sulfite source in aqueous solution remains unclear. In this work, employing solid CaSO₃ as a source of SO₃²⁻, we have studied the effects of different conditions (e.g., pH, Fe dosage, sulfite dosage) on As(III) oxidation in the Fe(III)–CaSO₃ system. The results show that 72.1% of As(III) was removed from solution by centrifugal treatment for 60 min at near-neutral pH. Quenching experiments have indicated that oxidation efficiencies of As(III) are due at 67.5% to HO^•, 17.5% to SO₅^•− and 15% to SO₄^•−. This finding may have promising implications in developing a new cost-effective technology for the treatment of arsenic-containing water using DG.     

Volume phase transition and structure of poly(N-isopropylacrylamide) microgels studied with 1H-NMR spectroscopy in D2O

Thermoresponsive colloidal microgels were prepared by polymerisation of N-isopropylacrylamide (NIPAM) with varying concentration of a cross-linking monomer, N,N-methylenebisacrylamide (MBA), in water with either 0.4 or 6.7 mM concentration of an anionic surfactant, sodium dodecylsulphate (SDS). Volume phase transitions of the prepared microgels were studied in D₂O by ¹H-NMR spectroscopy including the measurements of spin–lattice (T1) and spin–spin (T2) relaxation times for the protons of poly(N-isopropylacrylamide) (PNIPAM) at temperature range 22–50 °C. In addition, microcalorimetry, turbidometry, dynamic light scattering and electrophoretic mobility measurements were used to characterise the aqueous microgels. The results from the different characterisation methods indicated that PNIPAM microgels prepared in 6.7 mM SDS concentration are structurally different compared to their correspondences prepared in 0.4 mM concentration. Increasing MBA concentration in the microgel synthesis appears to increase the structural heterogeneity in both cases of SDS concentration. PNIPAM structures with significantly higher molecular mobilities at temperatures above 35 °C were observed in the microgels prepared in 0.4 mM SDS concentration, as indicated by the ¹H NMR relaxation times of different PNIPAM protons. We conclude that the high mobilities measured with NMR at elevated temperatures and also the clearly negative values of zeta potential are in connection to a fairly mobile surface layer with polyelectrolyte nature and a consequent high local lower critical solution temperature.     

Synthesis and characterization of some lanthanide(III) chelates of some schaffer acid azo dyes

Summary A series of trivalent lanthanide chelates of the type [Ln(PHNSA) (H₂O) _n ] (2 Cl) (whereLn ³⁺=Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb or Lu;PHNSA=2-(X)-phenylazo-2-hydroxynaphthalene-6-sulphonic acid;X=H, Cl, OCH₃, CH₃ and SO₃H) have been synthesized and characterized by elemental and thermal analysis, molar conductance, IR,¹H NMR (for diamagnetic complexes), electronic spectra and magnetic susceptibility measurements. IR data along with those of the¹H NMR unequivocally proved that the coordination of the ligands to the metal ions took place in a bidentate fashion through the oxygen of the hydroxyl group and the nitrogen of the azo group. The magnetic moment values showed little deviation from Van Vleck values.

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Synthese und Charakterisierung einiger Lanthaniden(III)-Chelate von Schaffersäure-Azofarbstoffen

Zusammenfassung Es wurde eine Reihe von dreiwertigen Lanthanidenchelaten des Types [Ln(PHNSA) (H₂O) _n ] (2 Cl) (mitLn ³⁺=Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb oder Lu undPHNSA=2-(X)-Phenylazo-2-hydroxynaphthalin-6-sulphonsäure,X=H, Cl, OCH₃, CH₃ und SO₃H) synthetisiert und mittels Elementar- und thermischer Analyse, molarer Leitfähgigkeit, IR,¹H-NMR (für diamagnetische Komplexe), Elektronenspektren und Messungen der magnetischen Suszeptibilität charakterisiert. Die IR-Daten zusammen mit¹H-NMR-Befunden zeigten eindeutig, daß die Koordinierung der Liganden zum Metallion zweizähnig durch den Sauerstoff der Hydroxylgruppe und den Stickstoff der Azo-Gruppe erfolgt. Die magnetischen Momente zeigten nur eine geringe Abweichung von den Van Vleck-Werten.

     

Synthesis,characterization, and insecticidal activity of new tin (IV) complexes

A three-component reaction of dimethyltin dibromide with imidazo[1,2-a]pyridine, pyridine derivatives, or isoquinoline and allyl bromide in refluxing ethanol affords the ionic complex, bis(1-allylcycloiminium) dimethyltetrabromostannate (II). The reaction involves N-allylation of cycloimine accompanied by the coordination of two bromide ions with the tin atom of dimethyltin dibromide. The complexes have been characterized by infrared and ¹H NMR, ¹³C NMR, and ¹¹⁹Sn NMR studies. The X-ray crystal structure analysis of a complex reveals the tin atom to be hexacoordinated and the dimethyltetrabromostannate (II) anion having octahedral geometry. Some of the complexes tested for their insecticidal activity are found to exhibit strong activity against Tribolium castaneum insect with LC₅₀ ranging from 0.4 to 0.8 ppm.     

The Affinity of Gallium(III) and Indium(III) for Nitrogen Donor Ligands

Abstract

Dedicated to Professor Arthur Martell on the occasion of his seventy fifth birthday.

The complexes of In(III) and Ga(III) with a variety of nitrogen donor ligands were studied in aqueous solution by glass electrode potentiometry at 25°C in 0.1 M NaNO₃. The ligands were 2-aminomethylpyri-dine (AMPY), ethylenediamine (EN), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (THPED), and N,N-bis(2-hydroxyethyl)glycine (BICIN). A variety of mixed ligand complexes of the MLOH type were detected with many of the above ligands as L. The logK₁ values obtained were with Ga(III) 8.40 (AMPY), 7.94 (THPED) 12.72 (EN), and In(III) 7.6 (AMPY), 8.20 (THPED), and 7.06 (BICIN). These formation constants are discussed in relation to previous predictions that In(III) and Ga(III) would have a substantial chemistry with nitrogen donor ligands. Of particular interest is the Ga(III) system with EN, where a very stable Ga(EN)³⁺ complex is formed, but no higher complexes except for hydrolyzed species such as Ga(EN)OH²⁺ and Ga(EN)(OH)₂ ⁺.