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1.
Voltammetric and potentiometric studies of some sulpha drug-Schiff base compounds and their metal complexes 总被引:1,自引:0,他引:1
M. M. Ghoneim E. M. Mabrouk A. M. Hassanein M. A. El-Attar E. A. Hesham 《Central European Journal of Chemistry》2007,5(3):898-911
The electrochemical behavior of some sulpha drug-Schiff bases at a mercury electrode was examined in the Britton-Robinson
universal buffer of various pH values (2.5–11.7) containing 20% v/v) of ethanol using DC-polarography, cyclic voltammetry
and controlled-potential electrolysis. The DC-polarograms and cyclic voltammograms of the examined compounds exhibited a single,
2-electron, irreversible, diffusion-controlled cathodic step within the entire pH range which is attributed to the reduction
of the azomethine group-CH=N- to -CH2-NH-. The symmetry transfer coefficient (α) of the electrode reaction and the diffusion coefficient (D
0) of the reactant species were determined. The electrode reaction pathway of the compounds at the mercury electrode was suggested
to follow the sequence: H+, e−, e−, H+. The dissociation constant of the sulpha drug-Schiff bases, the stability constant and stoichiometry of their complexes with
various divalent transition metal ions (Mn2+, Co2+, Ni2+, Cu2+ and Zn2+) were determined potentiometrically at room temperature.
相似文献
2.
A. A. El-Bindary I. S. Shehatta E. M. Mabrouk 《Monatshefte für Chemie / Chemical Monthly》1994,125(4):373-384
Summary Proton-ligand dissociation and metal-ligand stability constants of trithiocarbodiglycolic acid (TCGA) with some transition metal ions were calculated potentiometrically. The order of stability constants was found to be Fe3+ > Cu2+ > Ni2+ > Co2+. The effect of temperature on the stability of the complexes formed was studied and the corresponding thermodynamic functions were derived and discussed. Polarographic and cyclic voltammetric behaviours ofTCGA were investigated in B.R. buffer solutions ofpH 2–12. In solutions ofpH<8, the polarograms and cyclo-voltammograms exhibited a single 2-electron diffusion-controlled irreversible step, corresponding to the reduction of the C=S. The mechanism of the reduction process was postulated and the kinetic parameters of the electrode process were evaluated.
Thermodynamik der Komplexierung einiger Übergangsmetallionen mit Trithiocarbodiglykolsäure. Potentiometrische und voltammetrische Untersuchungen
Zusammenfassung Die Protonendissoziation vom Liganden und die Metall-Ligand-Stabilitätskonstanten von Trithiocarbodiglykolsäure (TCGA) mit einigen Übergangsmetallionen wurden potentiometrisch bestimmt. Die Reihung der Stabilitäten ist Fe3+ > Cu2+ > Ni2+ > Co2+. Die Temperaturabhängigkeit der Stabilitäten wurde gemessen und die entsprechenden thermodynamischen Funktionen abgeleitet. Das polarographische und cyclovoltammetrische Verhalten vonTCGA wurde in B.R.-Puffer beipH 2–12 ermittelt. In Lösungen vonpH<8 zeigten die Polarogramme und Cyclovoltagramme eine einzelne diffusionskontrollierte irreversible 2-Elektronen-Stufe, die der Reduktion von C=S entspricht. Es wurde ein Mechanismus postuliert und die kinetischen Parameter des Elektrodenprozesses wurden bestimmt.相似文献
3.
I. S. Shehatta A. M. Hassanein E. M. Mabrouk 《Monatshefte für Chemie / Chemical Monthly》1995,126(8-9):851-862
Summary UV spectra, dc polarograms, cyclic voltammetry and coulometry measurements of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone (H2
SPT) were recorded inBritton-Robinson buffer solutions ofpH 2–12. The dissociation constants of H2
SPT evaluated spectrophotometrically and potentiometrically in a 5% (v/v)DMF-water mixture are concordant. The dc-polarograms in solutions ofpH<8.5 exhibit a single 4-electron diffusion-controlled polarographic wave, whereas in solutions ofpH>8.5 two waves are observed. The cyclic voltammograms give a single cathodic peak in acidic and neutral solutions, whereas two cathodic peaks can be identified in alkaline ones. An electrode mechanism is proposed and discussed. The effect of temperature on the dissociation constants and the polarographic data was also investigated; the corresponding thermodynamic parameters were derived and are discussed.
Thermodynamische und voltammetrische Untersuchungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon
Zusammenfassung UV-Spektroskopische, dc-polarographische, voltammetrische und coulometrische Messungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon (H2 SPT) inBritton-Robinson-Pufferlösungen (pH 2–12) wurden durchgeführt. Die spektrophotometrisch und potentiometrisch ermittelten Dissoziationskonstanten von H2 SPT in 5% (v/v)DMF/Wasser stimmen überein. In Lösungen mit einempH-Wert unter 8.5 zeigen die dc-Polarogramme eine einzelne diffusionskontrollierte polarographische Welle (4e–), während in Lösungen mit einempH-Wert von über 8.5 zwei Wellen zu beobachten sind. Die cyclischen Voltammogramme weisen in sauren und neutralen Lösungen einen, in basischen Lösungen hingegen zwei kathodische Peaks auf. Ein Elektrodenmechanismus wird vorgeschlagen und diskutiert. Der Effekt der Temperatur auf die Dissoziationskonstanten und die polarographischen Ergebnisse wurde ebenfalls untersucht. Die entsprechenden thermodynamischen Größen wurden bestimmt und werden diskutiert.相似文献
4.
3-N-Substituted 5-(1Z-carboxymethylene)-2-chloro-4,4-dimethoxycyclopent-2-en-1-ones have been prepared from the corresponding 3-N-substituted 5-allenyl-2,5-dichloro-4,4-dimethoxycyclopent-2-en-1-ones using selective oxidative cleavage of their allene
bond by the RuCl3−NaIO4 system.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1646–1648, September, 1997. 相似文献
5.
Predrag Djurdjević Ratomir Jelić Ljubinka Joksović Mirjana Cvijović 《Monatshefte für Chemie / Chemical Monthly》2006,137(6):717-735
Summary. Solution equilibria between aluminium(III) ion and L-aspartic acid were studied by potentiometric, 27Al, 13C, and 1H NMR measurements. Glass electrode equilibrium potentiometric studies were performed on solutions with ligand to metal concentration
ratios 1:1, 3:1, and 5:1 with the total metal concentration ranging from 0.5 to 5.0 mmol/dm3 in 0.1 mol/dm3 LiCl ionic medium, at 298 K. The pH of the solutions was varied from ca. 2.0 to 5.0. The non-linear least squares treatment of the data performed with the aid of the Hyperquad program, indicated
the formation of the following complexes with the respective stability constants log βp,q,r given in parenthesis (p, q, r are stoichiometric indices for metal, ligand, and proton, respectively): Al(HAsp)2+ (log β1,1,1 = 11.90 ± 0.02); Al(Asp)+ (log β1,1,0 = 7.90 ± 0.03); Al(OH)Asp0 (log β1,1,−1 = 3.32 ± 0.04); Al(OH)2Asp− (log β1,1−2 = −1.74 ± 0.08), and Al2(OH) Asp3+ (log β2,1,−1 = 6.30 ± 0.04). 27Al NMR spectra of Al3+ + aspartic acid solutions (pH 3.85) indicate that sharp symmetric resonance at δ∼10 ppm can be assigned to (1, 1, 0) complex. This resonance increases
in intensity and slightly broadens upon further increasing the pH. In Al(Asp)+ complex the aspartate is bound tridentately to aluminum. The 1H and 13C NMR spectra of aluminium + aspartic acid solutions at pH 2.5 and 3.0 indicate that β-methylene group undergoes the most pronounced changes upon coordination of aluminum as well as
α-carboxylate group in 13C NMR spectrum. Thus, in Al(HAsp)2+ which is the main complex in this pH interval the aspartic acid acts as a bidentate ligand with –COO− and –NH2 donors closing a five-membered ring. 相似文献
6.
Voltammetry and electrochemical impedance spectroscopy were applied to investigate the inhibition activity of ethyleneglycol
and its oligomers on tin electrode in strong acidic sulfate solutions. Tetraethyleneglycol was found to be the most active
substance among compounds HO–(CH2–CH2–O)
m
–H (m≤4) that retards diffusion-controlled Sn(II) reduction due to its inhibitive adsorption. This rather slow process is controlled
both by diffusion and electrosorption steps. A comparison of exchange current densities obtained in the presence of different
polyethers shows that the length of the hydrocarbon chain is the main factor responsible for inhibition activity of such substances
on tin electrode. 相似文献
7.
A. N. Egorochkin S. E. Skobeleva T. G. Mushtina E. T. Bogoradovsky 《Russian Chemical Bulletin》1998,47(8):1526-1531
The integrated extinction coefficients (A) of the C≡C stretching modes in the IR spectra of 12 germylacetylenes Me3GeC≡CR are determined by the resonance interactions of substituents with the triple bond. TheA
1/2 values change linearly with change in the difference between the effective π-electron charges on the atoms at the triple
bond and σ0
R constants of organic substituents R. The average value of the σ0
R constant of the Me3Ge substituent in the compounds studied is +0.06. The resonance acceptor effect of the Me3Ge substituent toward the triple bond (d,π-conjugation) is stronger than the donor effect (σ,π-conjugation).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1569–1574, August, 1998. 相似文献
8.
The reaction of N-benzoylphosphoramidic dichloride with amines afforded some new N-benzoylphos-phoric triamides with formula C6H5C(O)NHP(O)(X)2, X=NH–CH(CH3)2 (1), NH–CH2–CH(CH3)2 (2), NH–CH2–CH(OCH3)2 (3), N(CH3)[CH2CH(OCH3)2] (4) and N(CH3)(C6H11) (5) that were characterized by 1H,13C,31P NMR, IR spectroscopy and elemental analysis. The structures have been determined for compounds 4 and 5 by X-ray crystallography. These compounds contain one amidic hydrogen atom and form centrosymmetric dimmers via intermolecular
–P–O⋯H–N–hydrogen bonds besides weak C–H⋯O hydrogen bonds that lead to three-dimensional polymeric clusters in the crystalline
lattice. 相似文献
9.
I. V. Oshanina N. A. Kokoreva L. G. Bruk O. N. Temkin I. L. Eremenko S. E. Nefedov 《Russian Chemical Bulletin》1998,47(11):2205-2207
A mixture of solid products was obtained upon absorption of dry HBr by MeCN. One of the products, [H2N=C(Me)−NH−C(Me)Br2]Br, was isolated as white single crystals and characterized by X-ray diffraction analysis.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2274–2277, November, 1998. 相似文献
10.
Mohamed El-Sayed Hardy Müller Gerd Rheinwald Heinrich Lang Stefan Spange 《Monatshefte für Chemie / Chemical Monthly》2003,134(3):361-370
Summary. N-(2′-Hydroxy-4′-N,N-dimethylaminobenzylidene)-4-nitroaniline [HDBN] has been used as a model for investigating intra- and intermolecular D–A (donor–acceptor) interactions in various environments
by means of UV/Vis spectroscopy. UV/Vis spectra of HDBN have been measured in various solvents, ethanolic solutions of different pH, adsorbed on silica, and in the solid state. A bathochromic shift of νmax is observed with increasing the dipolarity/polarizability and HBD (hydrogen bond donor) capacity of the solvent, which is
described by means of a multiple LSE (linear solvation energy) relationship in terms of the empirical Kamlet-Taft solvent polarity parameters. The adsorption of HDBN on Aerosil? 300-silica particles in non-HBA (hydrogen bond acceptor) solvents is explained in the same sense. Mobile protons and sol–gel
entrapping cause a hypsochromic shift due to protonation of the lone electron pair of the 4′-N,N-dimethylamino group. Hydroxide ions attack the 2′-hydroxy group which causes a bathochromic shift. A strong intramolecular
hydrogen bond between the 2′-hydroxyl hydrogen and the imine nitrogen atom is present in the solid-state structure causing
an unprecedented bathochromic shift.
Corresponding author. E-mail: stefan.spange@chemie.tu-chemnitz.de
Received July 8, 2002; accepted (revised) September 30, 2002 相似文献
11.
Samuel González-Mancebo Javier Lacadena Yolanda García-Alonso Jesús Hernández-Benito Emilio Calle Julio Casado 《Monatshefte für Chemie / Chemical Monthly》2002,133(2):157-166
Summary. Nitrosation reactions of phenol, o-cresol, 2,6-dimethylphenol, o-tert-butylphenol, 2-hydroxyacetophenone, and 2-allylphenol in water and water/acetonitrile were studied. Kinetic monitoring of
the reactions was accomplished by spectrophotometric analysis of the nitrosated products at 345 nm. The dominant reaction
was C-nitrosation via a mechanism consisting of an attack on the nitrosatable substrate by NO+/NO2H2
+ followed by a slow proton transfer. The values of the rate constants of phenolic C-nitrosation were increased by electron
donating substituents, and a good Hammett correlation was observed with ρ = −6.1. The results also revealed the strong effect of pH and the permitivity of the reaction medium on the rate constant, whose maximum values were observed for pH ≈ 3, decreasing strongly for higher pH values. The study in water/acetonitrile with up to 25% acetonitrile showed that it is possible to inhibit the reaction strongly
by increasing the percentage of the organic component. The conclusions drawn show that (i) it is possible to predict the rate of nitrosation of phenolics as a function of the meta-substituents on the phenol ring and (ii) the nitrosation of phenolics can be strongly inhibited by increasing the pH of the reaction medium as well as by lowering its dielectric constant.
Received July 13, 2001. Accepted (revised) September 18, 2001 相似文献
12.
Predrag Djurdjevi? Ratomir Jeli? Ljubinka Joksovi? Mirjana Cvijovi? 《Monatshefte für Chemie / Chemical Monthly》2006,12(2):717-735
Solution equilibria between aluminium(III) ion and L-aspartic acid were studied by potentiometric, 27Al, 13C, and 1H NMR measurements. Glass electrode equilibrium potentiometric studies were performed on solutions with ligand to metal concentration
ratios 1:1, 3:1, and 5:1 with the total metal concentration ranging from 0.5 to 5.0 mmol/dm3 in 0.1 mol/dm3 LiCl ionic medium, at 298 K. The pH of the solutions was varied from ca. 2.0 to 5.0. The non-linear least squares treatment of the data performed with the aid of the Hyperquad program, indicated
the formation of the following complexes with the respective stability constants log βp,q,r given in parenthesis (p, q, r are stoichiometric indices for metal, ligand, and proton, respectively): Al(HAsp)2+ (log β1,1,1 = 11.90 ± 0.02); Al(Asp)+ (log β1,1,0 = 7.90 ± 0.03); Al(OH)Asp0 (log β1,1,−1 = 3.32 ± 0.04); Al(OH)2Asp− (log β1,1−2 = −1.74 ± 0.08), and Al2(OH) Asp3+ (log β2,1,−1 = 6.30 ± 0.04). 27Al NMR spectra of Al3+ + aspartic acid solutions (pH 3.85) indicate that sharp symmetric resonance at δ∼10 ppm can be assigned to (1, 1, 0) complex. This resonance increases
in intensity and slightly broadens upon further increasing the pH. In Al(Asp)+ complex the aspartate is bound tridentately to aluminum. The 1H and 13C NMR spectra of aluminium + aspartic acid solutions at pH 2.5 and 3.0 indicate that β-methylene group undergoes the most pronounced changes upon coordination of aluminum as well as
α-carboxylate group in 13C NMR spectrum. Thus, in Al(HAsp)2+ which is the main complex in this pH interval the aspartic acid acts as a bidentate ligand with –COO− and –NH2 donors closing a five-membered ring. 相似文献
13.
The flotation kinetics of coarse coal particles was studied in a modified version of the Hallimond tube at 25 °C using nitrogen
as the carrier gas, in the pH range 2–12. The kinetics was followed by measuring the volume of the particles accumulated in
the collector tube as a function of time. At each pH, the rate constants were determined at several buffer concentrations
and were extrapolated to zero buffer concentration. The observed first-order rate constant was represented as the product
of separable constants and functions such as f
D, f
V and f
pH, which depend only on the particle size, gas flow and the pH of the dispersion, respectively. The diameter, D, of the particles was in the range 505–127 μm. The observed rate constant decreased linearly with the diameter of the particles
at constant flow and it was calculated that f
D=exp(−1.56D). The dependence of f
V on the flow is a consequence of the fact that the flotation occurs when a single particle is captured by two bubbles. f
V was shown to be independent of the particle diameter. The effect of the pH on the rate of flotation was considered as resulting
from the adsorption of protons (or hydroxide ions) by the particles and bubbles through multiple equilibria, assuming that
there is no interaction between the binding sites. The pH–rate profile showed that there were two species responsible for
the flotation: one stable at pH below 5 and the other at high pH. Comparison of f
V, f
D and f
pH for the flotation of coal and pyrite allowed the prediction of the optimum conditions for the separation of mixtures of these
particles by flotation.
Received: 6 August 2001 Accepted: 19 September 2001 相似文献
14.
A scheme of consitent quantum-chemical calculations of constants of isotropic hyperfine coupling (IHFC) with protons (a
H
iso
) in free radicals is considered for the case where the spin populations ρs
H are determined in the basic set of symmetrically orthogonalized atomic orbitals taking model σ-and π-electron fragments as
an example. The competence of using two coefficients of proportionalityK(H) when estimating the proton IHFC constants by semiempirical quantum-chemical methods was demonstrated. Theoretical substantiation
of empirical values of the above coefficients previously used is revealed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 245–249, February, 1999. 相似文献
15.
Summary. A crystal structure determination of a bilirubin analog with a sulfur instead of a C(10)–CH2 linking the two dipyrrinones is reported. Conformation-determining torsion angles and key hydrogen bond distances and angles
are compared to those obtained from molecular dynamics calculations as well as to the corresponding data from X-ray determinations
and molecular dynamics calculations of bilirubin. Like other bilirubins, the component dipyrrinones of the analog are present
in the bis-lactam form with (Z)-configurated double bonds at C(4) and C(15). Despite the large differences in bond lengths and angles at –S–vs.–CH2–, the crystal structure shows considerable similarity to bilirubin: both pigments adopt a folded, intramolecularly hydrogen-bonded
ridge-tile conformation stabilized by six hydrogen bonds – although the interplanar angle of the ridge-tile conformation of
the title compound is smaller (∼ 86°) than that of bilirubin (∼ 98°). The collective data indicate that even with long C–S
bond lengths and a smaller C–S–C bond angle at the pivot point on the ridge-tile seam, intramolecular hydrogen bonding persists.
Received August 16, 2001. Accepted September 12, 2001 相似文献
16.
Sham M. Sondhi Monika Johar Nidhi Singhal Sunanda G. Dastidar Rakesh Shukla Ram Raghubir 《Monatshefte für Chemie / Chemical Monthly》2000,131(5):511-520
Summary. Various sulfa drugs were condensed with 4-isothiocyanato-4-methyl-2-pentanone at pH∼3–5 by refluxing in methanol to give various substituted mercaptopyrimidines. On condensation with 9-chloro-2-substituted
or -unsubstituted acridines, sulfathiazole gave the corresponding condensed products. N-Ethylaminoadenosine reacted with 9-chloroacridine
to the coupled product. Condensation of sulfathiazole with 9-isothiocyanato-2,4-substituted or -unsubstituted acridines afforded
the corresponding condensed compounds. The structures of all synthesized compounds were confirmed by spectroscopic methods.
Anticancer, antiinflammatory, and analgesic activities of all compounds were investigated.
Received November 18, 1999. Accepted (revised) January 12, 2000 相似文献
17.
N. A. Ustynyuk M. G. Peterleitner O. V. Gusev L. I. Denisovich 《Russian Chemical Bulletin》1993,42(10):1727-1730
The electrochemical behavior of rhodium sandwich complexes containing η4-pentamethylcyclopentadiene or tetramethylfulvene fragments has been studied by cyclic voltammetry. The complexes undergo
one-electron oxidation to give unstable 17-electron radical cations which are converted into rhodocenium salts as a result
of elimination or uptake of hydrogen or C-C bond cleavage.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1802–1805, October, 1993. 相似文献
18.
M. Z. Kassaee M. R. Momeni F. A. Shakib M. Ghambarian S. M. Musavi 《Structural chemistry》2009,20(3):517-524
Biologically important bicyclic species, including 6H-, 6H-6-aza-, and 6-oxabenzocycloheptatrienes (in which the benzene moiety is fused meta with respect to the tetrahedral constituents: –CH2–, –NH–, and –O–, respectively), show strong shifts of tautomerizations in favor of the corresponding tricyclic benzonorcaradienes
(with ΔH values of −11.49, −14.55, and −19.20 kcal mol−1, respectively), at B3LYP/6-311++G**//B3LYP/6-31G*, and MP2/6-311++G**//MP2/6-31G* levels, and at 298 K. In contrast, such
shifts are strongly disfavored by the isomeric bicyclic species in which the benzene moieties are fused ortho or para with respect to –CH2–, –NH–, and –O–, respectively. Hence for species with ortho benzene rings including 5H-, 5H-5-aza- and 5-oxabenzocycloheptatrienes, tautomerization ΔH values are 30.76, 31.89, and 25.27 kcal mol−1, respectively, while for species with para fused benzene moieties including 7H-, 7H-7-aza-, and 7-oxabenzocycloheptatrienes, tautomerization ΔH values are 24.12, 26.00, and 19.55 kcal mol−1, respectively. NICS calculations are successfully used to rationalize these results. The calculated energy barriers for inversion
of the seven-membered rings of bicyclic species predict a dynamic nature for all the structures except for the virtually planar
6H-6-aza- and 6-oxabenzocycloheptatrienes. Finally, our theoretical data are compared to the experimental results where available.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Hasan Marai Ewa Kita Emilia Kiersikowska Sylwia Kuchta Anna Bajek Tomasz Drewa 《Transition Metal Chemistry》2012,37(4):337-344
Three chromium(III) complexes with asparagine (Asn) and histidine (His) of the [Cr(ox)2(Aa)]2− type, where Aa = N,O–Asn, N,O–His or N,N′–His, were obtained and characterized in solution. The complexes with N,O–Aa undergo acid-catalysed aquation to give a free amino acid and cis-[Cr(ox)2(H2O)2]−, whereas the complex with N,N′–His undergoes parallel reaction paths: (1) isomerization to the N,O–His complex and (2) liberation of an oxalate ligand. Kinetics of the N,O–Aa complexes in HClO4 media were studied spectrophotometrically under pseudo-first-order conditions. The absorbance changes were attributed to
the chelate ring opening at the Cr–N bond. The linear dependence of rate constants on [H+] was established, and a mechanism for the chelate ring cleavage was postulated. The existence of a metastable intermediate
with O-monodentate Aa ligand was proved experimentally. Effect of [Cr(ox)2(Aa)]2− on 3T3 fibroblasts proliferation was studied. The tests revealed low cytotoxicity of the complexes. Complexes with Ala, His
and Cys are good candidates for biochromium sources. 相似文献
20.
Bikshandarkoil R. Srinivasan Christian Näther Sunder N. Dhuri Wolfgang Bensch 《Monatshefte für Chemie / Chemical Monthly》2006,137(4):397-411
Summary. Four new organic ammonium tetrathiotungstates (N–Me–enH2)[WS4] (1), (N,N′-dm-1,3-pnH2)[WS4] (2), (1,4-bnH2)[WS4] (3), and (mipaH)2[WS4] (4), (N–Me–enH2 = N-methylethylenediammonium, N,N′-dm-1,3-pnH2 = N,N′-dimethyl-1,3-propanediammonium, 1,4-bnH2 = 1,4-butanediammonium, and mipaH = monoisopropylammonium) were synthesized by the base promoted cation exchange reaction and characterized by elemental analysis,
infrared, Raman, UV-Vis and 1H NMR spectroscopy as well as single crystal X-ray crystallography. The structures of 1–4 consist of [WS4]2− tetrahedra which are linked to the organic ammonium cations via N–H⋯S hydrogen bonding. The strength and number of the S⋯H
interactions affect the W–S bond lengths as evidenced by distinct short and long W–S bonds. The IR spectra exhibit splitting
of the W–S vibrations, which can be attributed to the distortion of the [WS4]2− tetrahedron. From a comparative study of several known tetrathiotungstates it is observed that a difference of more than
0.033 ? between the longest and shortest W–S bonds in a tetrathiotungstate will result in the splitting of the asymmetric
stretching vibration of the W–S bond. 相似文献