The effect of selfassociation of mercurated carbonyl compounds of mercury-199 chemical shifts

Temperature and concentration dependences of mercury-199 chemical shifts in benzene solutions of bis(methylethylketone)mercury Hg(CH₂COC₂H₅) (I) and α-bis(methylacetoacetone)mercury Hg(CH₂COCH₂COOCH₃)₂ (II) are determined by the ¹H-{¹⁹⁹Hg}method. The NMR data obtained and the IR spectra are indicative of selfassociation of I and II in solution with the formation of weak intermolecular coordination bonds Hg ← :OC. The enthalpies of complex formation calculated on the assumption of one mercury atom bonding with only one carbonyl function are equal to ?3.2 ± 0.1 kcal/mol and ?2.2 ± 0.1 kcal/mol for I and II, respectively.     

Diiodobis(diphenyltelluride)mercury(II), [(Ph2Te)2HgI2]

Diiodobis(diphenyltelluride)mercury(II), [(Ph₂Te)₂HgI₂], is formed during the reaction of [(PhTe)₂Hg] with HgI₂ in refluxing THF. The same product can be obtained from a pressure reaction between PhTeI₃ and elemental mercury. The mercury atom is co‐ordinated in a distorted tetrahedral environment with I‐Hg‐I angles of 117?. Long range I···Te contacts of about 3.8 Å link the [(Ph₂Te)₂HgI₂] units to infinite chains along the b axis of the unit cell.     

Newly observed surface-solution oscillating reaction: Mercury-catalyzed dissolution of aluminium in nitric acid

Aluminium metal is dissolved in 3 M HNO₃ with mercury(II) nitrate as a catalyst. Visible oscillations in gas evolution are observed for 2×10^–4 M Hg(NO₃)₂ dissolving solutions. The oscillations are followed quantitatively by monitoring both solution temperature and the intensity of a UV-visible transmittance peak at 369 nm. This peak is attributed to mercury(I) species in solution.     

Effect of terminal groups on the relative stability of linear mercury clusters

The problem of stabilizing the linear clusters of mercury by terminal groups is discussed in terms of the MNDO method for the following model and real compounds: Hg_n (I), Hg_nCl₂ (II) and Hg_n(AlCl₄)₂ (III) with n=2–4. It is shown that the terminal acceptor groups stabilize the linear mercury chains. It is established that in systems (II) and (III), unlike in (I), the highest occupied molecular orbitals are bonding. Mordoviya State University. Institute of Organoelement Compounds, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 4, pp. 623–629, July–August, 1995. Translated by I. Izvekova     

The crystal structures of two Mercury Perrhenates

The mercury perrhenates with the empirical formulas HgReO₄ and Hg₂ReO₅ were prepared by annealing powdered mixtures of mercury(II)oxide and mercury(II)metaperrhenate Hg(ReO₄)₂ in sealed silica tubes. Their crystal structures were determined from single-crystal X-ray data. HgReO₄ crystallizes dimeric with nearly linear O₃Re? O? Hg? Hg? O? ReO₃ molecular units and Hg₂ReO₅ has a solid state structure, where Hg(I) and Hg(II) together with oxygen atoms form 14-membered rings, which are condensed to two-dimensionally infinite polycationic nets of composition (Hg₂²⁺ · 2 HgO)_n. These nets are separated from each other by tetrahedral ReO₄^? anions.     

Preparation,infrared, Raman and N.M.R. spectra of N,N′-Diethylthiourea complexes with zinc(II), cadmium(II) and mercury(II) halides

Several complexes of N,N′-diethylthiourea (Dietu) with zinc(II), cadmium(II) and mercury(II) halides were prepared and characterized by i.r. (4000–60 cm^?1), raman (400–60 cm^?1), in the solid state and n.m.r. and conductometric methods in solution. The complexes Zn(Dietu)₂X₂, Cd(Dietu)₂X₂ (X ? Cl, Br, I) and Hg(Dietu)₂X₂ (X ? Br, I) are tetrahedral species in which intramolecular ? NH …? X interactions have been observed. The 1:1 mercury(II) complexes, Hg(Dietu)X₂ (X ? Cl, Br), appear to have a dimeric tetrahedral halide-bridged structure in the solid state. In all these complexes N,N′-diethylthiourea is sulphur-bonded to the metal.     

Synthesis of 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione and structural characterization of its polymorphs and complexes with 12-group metal iodides

A novel cyclic thiourea, 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione (L), was synthesized by the reaction of N-(1-tosylethyl)thiourea with potassium enolate of acetylacetone followed by acid-catalyzed dehydration of the obtained 5-acetyl-4-hydroxy-4,6-dimethylhexahydropyrimidine-2-thione. Its polymorphs and complexes with zinc, cadmium, and mercury iodides were studied by X-ray diffraction. Two polymorphs of 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione differ in ring conformation and packing manner. In the monomeric cadmium complex [CdL₂I₂], the central atom is tetrahedrally coordinated in the standard manner by iodine and thiocarbonyl S atoms, while in the dimeric mercury complex [Hg₂L₂I₄], every mercury atom is coordinated by two bridging I atoms, one terminal I atom and one thiocarbonyl S atom of the ligand. In the polymeric zinc complex [ZnLI₂], the zinc tetrahedra are linked by the bidentate bridging 5-acetyl-4,6-dimethyl-1,2,3,4-tetrahydropyrimidine-2-thione molecules through thiocarbonyl S atom and acetyl O atom.     

Reactions of silylmercury compounds with sodium and potassium in the aromatic solvents

Bis(triethylsilyl)mercury (I) and triethylsilyl(pentaethyldisilanyl)mercury (II) react with metallic sodium or potassium in benzene solution to give phenyltriethylsilane (III) and a mixture of III and 1-phenyl-2,2,3,3,3-pentaethyldisilane, respectively, instead of the expected silylmetallic compounds (e.g. Et₃SiM and Et₅Si₂M, where M = Na or K). These results may be explained by the intermediate formation of silylmetallic compounds which reacted with the solvent. The reaction of I with potassium in toluene proceeds analogously.     

Electrochemical reduction of the perfluoro-n-Hexyl iodide on mercury,in dimethylformamide

The electrochemical reduction behaviour of perfluoro-n-hexyl iodide, C₆F₁₃I, has been studied at the mercury electrode in dimethylformamide as a solvent. The major reaction product of the controlled-potential electrolysis of C₆F₁₃I is the organomercuric compound (C₆F₁₃)₂Hg. Using conventional polarography and linear sweep voltammetry, it is concluded that a chemical prereaction occurs between the perfluoro-n-hexyl iodide and polarized mercury, yielding the perfluoro-n-hexyl mercury iodide C₆F₁₃HgI, which is itself reducible in two separate steps. A detailed mechanism of the electrochemical reduction of C₆F₁₃I is proposed and discussed.     

Crystal chemistry of mercury(I) and mercury(I, II) minerals

The crystal structures of 16 mercury(I)- and mercury(I, II)-containing minerals having (Hg-Hg)²⁺ groups are considered. The Hg-Hg and Hg-X bond lengths and the HgHgX angles (X = Cl, Br, I, O, S) are analyzed. A comparative crystal chemical analysis of the environment of Hg atoms is carried out. The Hg-Hg and Hg-X distances vary within 2.43-2.60 and 1.93-2.43 å, respectively; the angles defining the deviation of the X-Hg-Hg-X groups from linearity are from 146 to 177?. In most cases, the coordination environment of the mercury atoms involves the metal atom of the (Hg-Hg)²⁺ dumbbell and the X atom, but in several compounds the coordination number of the mercury atoms increases due to the additional atoms lying 2.5–3.5 å away. In terlinguaite and kuznetsovite, the Hg₃ triangle is rather unusual; in the latter mineral, the Hg-Hg bonds are lengthened to 2.64-2.70 å. The review covers structural data up to May 1997.     

Determination of sulfite by reaction with mercury(I) chloride and spectrophotometric measurement of mercury(II) complexes

Sulfite ion was determined in the 0.4 to 12-ppm range by reaction with insoluble mercury(I) chloride to form the soluble Hg(SO₃)₂^staggered2? ion and elemental mercury. The uv absorption of the sulfite complex or an anion species, HgX₄^staggered2?, formed on adding an excess of KBr, KCl, KI, or KSCN is measured. The mercury(II) in solution can also be determined by lowering the pH, adding KCl, and forming the crystal violet adduct of the HgCl₃^staggered? ion. This adduct is extracted into benzene and the absorbance measured at 605 nm.     

Dual-wavelength spectrophotometric determination of traces of mercury(II) with solubilized dithizone: An approach to simplified analytical procedures for environmental pollutants

A simple spectrophotometric procedure is described for the determination of traces of mercury, with solubilized copper(II) dithizonate. Sample water containing 0.05–0.25 μg of mercury(II) is mixed with an aqueous solution of copper dithizonate containing Triton X-100 at pH 1 (H₂SO₄ ). After 5 min, dual-wavelength photometry is used to measure the difference in absorbances at 507 and 493 nm, which is proportional to the mercury concentration. The advantages are that no reagent blank is necessary and the equipment is simple. Few cations interfere; silver(I) and iron(III) can be masked by chloride and fluoride, respectively.     

Thermal decomposition of silver(I) and mercury(I) anthranilates and salicyloaldoximates

The processes of thermal decomposition of silver(I) and mercury(I) anthranilates and salicyloaldoximates were studied. Thermal, chemical and X-ray analyses and infrared spectroscopy were used to determine the mechanisms of decomposition of these complexes. The factor determining the decomposition is the character of the Ag⁺ and Hg ₂ ²⁺ ions, which are easily reduced to free metals. The final reaction product of the compounds of silver is the pure metal; the compounds of mercury are volatilized completely when heated.     

Mechanistic insights into the reaction of CF3CCl3 with SO3: Theory and experiment

Reaction mechanism of 1,1,1-trifluorotrichloroethane (CF₃CCl₃) and sulphur trioxide (SO₃) in the presence of mercury salts (Hg₂SO₄ and HgSO₄) was studied applying the density functional theory (DFT) at the UB3LYP/6-31+G(d,p) level. It was found that this reaction occurs in the free radical chain path as follows: mercury(I) sulphate free radical is generated by heat, causing CF₃CCl₃ to produce the CF₃CCl₂ free radical which reacts with SO₃ leading to the formation of CF₃CCl₂OSO₂ decomposing into CF₃COCl and SO₂Cl. The SO₂Cl free radical triggers CF₃CCl₃ to regenerate CF₃CCl₂ which recycles the free radical growth reaction. This elementary reaction has the highest energy barrier and it is therefore the rate control step of the whole reaction path. Experiment data can confirm the existence of the mercury(I) salt free radical and the free radical initiation stage. So, mercury salts play the role of initiators not that of catalysts. The results agree well with our hypothesis.     

Syntheses,Characterization, and Crystal Structures of a Dinuclear Complex and Coordination Polymer of Mercury(II) with Schiff Base Ligands containing N3 and N4 Donors

Two dinuclear mercury(II) iodide compounds, [Hg₂(L)(I)₄] ( 1 ) and [(L′)Hg(μ‐I)₂HgI₂]_n ( 2 ) [L = N,N′‐bis(phenyl(pyridin‐2‐yl)methylene)propane‐1,2‐diamine and L′ = N‐(phenyl(pyridin‐2‐yl)methylene)propane‐1,2‐diamine] were synthesized and characterized. The molecular structures of [Hg₂(L)(I)₄] ( 1 ) and [(L′)Hg(μ‐I)₂HgI₂]_n ( 2 ), which were determined by single‐crystal X‐ray diffraction, indicate that each Hg^II in 1 has a distorted tetrahedral environment around the metal atom with a HgN₂I₂ chromophore, whereas in 2 one mercury(II) atom adopts a distorted tetrahedral arrangement with a HgI₄ chromophore and the other has a distorted square pyramidal environment with HgN₃I₂ chromophore. In the solid state, compound 2 consists of a 1D coordination polymer structure.     

Electrochemistry of copper in aqueous acetonitrile

The electrochemical characteristics of the Cu (II)/Cu (I) and the Cu (I)/Cu (0) couples at platinum, carbon, mercury and copper have been studied in acetonitrile-water (AN-H₂O) mixtures. All the electrode processes are moderately fast with mercury the fastest but slower on platinum and carbon paste in that order. A slow chemical step precedes oxidation of Cu (I) to Cu (II) on allectrodes in solutions of high AN content. The slow step may be partial removal of AN from the solvated Cu (I) ion prior to electron transfer. Electrode processes are faster in chloride ions than in sulfate ion solutions. Reduction of Cu (I) in AN–H₂O is quite slow on glassy carbon. Adsorption of AN on platinum and carbon influences the processes. Diffusion coefficients in sulfate solutions are in the order, Cu (I) (AN–H₂O)>Cu (II)(AN–H₂O)>Fe (III)(H₂O) and 2-hydroxy-cyanoethane (2-HCE) strongly decreases the mobility of Cu (I) when added to H₂O. The relevance of the measurements to hydrometallurgical processes is considered. CuSO₄ in 30% v/v AN–H₂O is a faster oxidant than the common oxidant Fe₂(SO₄)₃ in H₂O because of the greater mobility and faster electron acceptance from a corroding surface of Cu (II). Only in solutions of very high nitrile content is the reduction potential of CuSO₄ as high as that of Fe₂(SO₄)₃ in H₂O.     

Determination of mercury species in gas condensates by on-line coupled high-performance liquid chromatography and cold-vapor atomic absorption spectrometry

A method for the speciation of mercury in gas condensates is reported. Mercury(II) chloride (HgCl₂), methylmercury chloride (MeHgCl), phenylmercury acetate (PhHgAc) and diphenylmercury (Ph₂Hg) are separated by reversed-phase high-performance liquid chromatography (HPLC) using gradient elution. Prior to the determination, the organic ligands and the matrix were destroyed by oxidation with K₂Cr₂O₇. Mercury is detected with cold-vapor atomic absorption spectrometry (CVAA), where the mercury compounds are reduced to metallic mercury by a treatment with NaBH₄. In a continuous-flow system the concentrations of the reagents used are optimized using a modified simplex algorithm. Detection limits for mercury are at the 10 ng ml^?1 level. Analysis of multi-compound mixtures indicates that chemical reactions between HgCl₂ and Ph₂Hg and between MeHgCl and Ph₂Hg take place. The method developed was applied to the speciation of mercury in gas condensates and did not require use of any solvent extraction or chemical derivatization steps. In the gas condensates, mercury(II) compounds were found to be present at the 100 ng ml^?1 level.     

The polarographic and voltammetric behaviour of acetylacetonato and hexafluoroacetylacetonato complexes in acetonitrile

The polarographic behaviour of Ce(acac)₄, Ce(acac)₃, Eu(acac)₃, Fe(acac)₃, Cr(acac)₃, Co(acac)₃, Mn(acac)₃, NaMn(acac)₃, Mn(acac)₂, Ni(acac)₂, Cu(acac)₂, VO(acac)₂, Fe(hfacac)₃, Cr(hfacac)₃ and Cu(hfacac)₂ has been studied in acetonitrile on the dropping mercury electrode. Half-wave potentials versus bisbiphenylchromium(I)/(0), the reversibility of the electrode reaction and the number of electrons participating in the electrode processes measured by coulometry are reported. Cyclovoltammetric measurements have been performed on the hanging mercury drop electrode and on the stationary platinum electrode, the data of these studies are given. quite different behaviour has been observed on the platinum electrode compared to the dropping mercury electrode. Large scale electrolysis was employed to obtain information on the reaction products. The influence of the electrode material and the reaction mechanisms are discussed.     

Complexes of zinc,cadmium and mercury(II) with the zwitter-ionic form of NN′-ethylenebis (salicylideneimine)

The Schiff base NN′-ethylenebis(salicylideneimine), H₂ salen reacts with hydrous and anhydrous Zinc, Cadmium and Mercury(II) salts to give complexes M(H₂ salen)X₂·nH₂O (M = Zn, Cd, Hg; XCl, Br, I, NO₃; MZn, X₂SO₄; n = 0?2). Spectroscopic and other evidence indicated that; (i) halide and sulphate are coordinated to the metal ion, whereas the nitrate group is ionic in mercury nitrate compound and covalently bonded in zinc and cadmium nitrato complexes, (ii) the Schiff base is coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms, which carry the protons transferred from phenolic groups on coordination, (iii) therefore the coordination numbers suggested are 4-, in mercury and 4- or 6- in zinc and cadmium Schiff base complexes.     

Séparation de traces métalliques sur goutte de mercure; application à la préconcentration de Cu(II) et Cu(I)

A method for the rapid separation of copper(II) traces on metallic mercury is proposed. The separation is rendered possible by the reduction of Cu(II) to Cu(I) on mercury in the presence of iodide ions followed by the adsorption of the uncharged complex, Cu(I), on Hg⁰. After a minute of agitation, this adsorption is quantitative (90–100%) for initial concentrations of Cu(II) between 10^?4 to 10^?6 M and iodide cone, of 10^?2 to 10^?3 M at pH 3. The volumes of the aqueous solutions are of the order of 3–10 ml and those of the drops of mercury between 0.5–1 ml. The tests were made using the isotope ⁶⁴Cu (T _1/2 = 12.8 h).