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.     

Lead(II) complexes of 2,2′-diamino-4,4′-bithiazole (DABTZ) including crystal structure of a novel 1D chain polymer, [PB(DABTZ)(μ-SCN)(μ-NO3)] n

Three new 2,2′-diamino-4,4′-bithiazole (DABTZ) lead(II) complexes were synthesized and characterized by elemental analyses, IR-, ¹H-NMR-, and ¹³C-NMR-spectroscopy. The single crystal X-ray structural analysis of [Pb(DABTZ)(μ-SCN)(μ-NO₃)] _n shows the complex to be a 1D chain polymer as a result of sequential thiocyanate and nitrate bridging. The Pb atoms are seven-coordinated by two nitrogen atoms of the 2,2′-diamino-4,4′-bithiazole, three nitrate and two thiocyanate ligands. The arrangement of the 2,2′-diamino-4,4′-bithiazole, nitrate and thiocyanate ligands does not suggest a gap in the coordination around the Pb^II ion, caused by a stereo-active lone pair of electrons on lead(II) where the coordination around the lead atoms is the less common holodirected.     

Determination of mono-, di- and tri-substituted butyltin,phenyltin and methyltin compounds as free halides using gas chromatography with flame photometric detection

A simple chromatographic procedure has been developed for the sensitive determination of mono-, di- and tri-substituted butyltin, phenyltin, and methyltin compounds as halides. The organotin compounds were separated on a DB-1 capillary column and detected by flame photometric detection (FPD) equipped with a 611.5 nm filter. Pretreatment of the capillary column with an ethyl acetate solution of hydrobromic acid, or doping of standard solutions with hydrobromic acid, was found to be necessary if reproducibly sharp peaks of organotin halides were to be obtained. Column treatment and acid doping did not cause any background problems or undesirable degradation of the organotin compounds. Three different standard solutions in ethyl acetate had to be Jrepared, because undesirable degradation of the organotin halides was observed when all the compounds were dissolved in the same solution. The first, standard solution I, contained tri-n-butyltin chloride (TBTCI) and trimethyltin chloride (TMTCI), the second, standard solution II, contained triphenyltin chloride (TPTCI), and the third, standard solution III, contained hydrogen bromide and the other organotin compounds: di-n-butyltin chloride (DBTCI), mono-n-butyltin chloride (MBTCI), dimethyltin chloride (DMTCI), monomethyltin chloride (MMTCI), diphenyltin chloride (DPTCI), and monophenyltin chloride (MPTCI). An ethyl acetate solution containing hydrobromic acid (20 × 10^?3 mol/I) was used for column treatment.     

Preparation and Spectral Investigation of Bis[N(2-methyl-phenyl) 4-Nitro-thiobenzamidato] mercury(II), Bis[N(2-methoxy-phenyl) 4-Nitro-thiobenzamidato]mercury(II), and Bis[N(2-chloro-phenyl) 4-Nitro-thiobenzamidato]mercury(II) Complexes

Several preparative routes to bis[N(substituted-phenyl) 4-nitro-thiobenzamidato] mercury(II) complexes are presented, including the reaction of mercury(II) oxide, fluoride, chloride, bromide, cyanide, acetate, and nitrate with N(substituted-phenyl) 4-nitro-thiobenzamide derivatives. ¹ H-NMR, Raman, and IR measurements confirmed the complexation of mercury to sulphur.     

Preparation,characterization, DFT calculations and ethylene oligomerization studies of iron(II) complexes bearing 2-(1H-benzimidazol-2-yl)-phenol derivatives

Five 2-(1H-benzimidazol-2-yl)-phenol derivatives including 1H (HL₁), 5-chloro-(HL₂), 5-methyl-(HL₃), 5,6-dichloro-(HL₄), and 5,6-dimethyl-(HL₅) were synthesized by the reaction of their corresponding benzene-1,2-diamine precursors and 2-hydroxybenzaldehyde which subsequently was employed in complexation with Fe(II) to prepare complexes C1–C5, respectively. Indeed, in all complexes, the ligands were coordinated as bidentate, via the C=N nitrogen and hydroxy oxygen atom of benzimidazole moiety and phenol ring, respectively. The compounds were characterized by FTIR, UV–vis, ¹H- and ¹³C-NMR spectropscopy, ICP, and elemental analysis (C, H, and N). The purity of these compounds was determined by melting point (m.p )and TLC. The synthesized ligands and complexes were geometrically optimized by Gaussian09 software at B3LYP/TZVP level of theory and satisfactory theoretical–experimental agreement was achieved for analysis of IR data of the compounds. Catalytic behavior of the iron(II) complexes was investigated for ethylene reactivity. On activation with diethylaluminum chloride (Et₂AlCl), iron(II) complex (C4) showed the highest activity (1686 kg oligomers.mol^?1(Fe).h^?1) for ethylene oligomerization when it contains chlorine substituents and exhibits good selectivity for linear 1-butene. The steric and electronic effects of ligands were investigated in detail on the influence of their catalytic activities.     

Two new zinc(II) and mercury(II) complexes based on N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide): synthesis,crystal structures and antibacterial activities

Reaction of N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide), C₂₀H₁₈F₂N₄O₂, ( L^F ), with zinc chloride and mercury(II) chloride produced different types and shapes of neutral coordination complexes, namely, dichlorido[N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide)‐κ²N,O]zinc(II), [ZnCl₂(C₂₀H₁₈F₂N₄O₂)], ( 1 ), and dichlorido[N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide)‐κ⁴O,N,N′,O′]mercury(II), [HgCl₂(C₂₀H₁₈F₂N₄O₂)], ( 2 ). The organic ligand and its metal complexes are characterized using various techniques: IR, UV–Vis and nuclear magnetic resonance (NMR) spectroscopies, in addition to powder X‐ray diffraction (PXRD), single‐crystal X‐ray crystallography and microelemental analysis. Depending upon the data from these analyses and measurements, a typical tetrahedral geometry was confirmed for zinc complex ( 1 ), in which the Zn^II atom is located outside the bis(benzhydrazone) core. The Hg^II atom in ( 2 ) is found within the core and has a common octahedral structure. The in vitro antibacterial activities of the prepared compounds were evaluated against two different bacterial strains, i.e. gram positive Bacillus subtilis and gram negative Pseudomonas aeruginosa bacteria. The prepared compounds exhibited differentiated growth‐inhibitory activities against these two bacterial strains based on the difference in their lipophilic nature and structural features.     

含氮五元杂环酮的拟除虫菊酯的合成、结构和生物活性

以1-对乙氧基-2,2-二氯环丙烷甲酸(1a)和3-(2-氯-3,3,3-三氟-1-丙烯)-2,2-二甲基环丙烷甲酸(1b)为原料, 经酰氯化反应得到酰氯, 再以三乙胺为缚酸剂, 分别与2-烷酮、2-噻唑烷酮、2-噻唑硫酮、1-乙酰基-2-咪唑烷酮、1-甲磺酰 基-2-咪唑烷酮反应, 得到10个新的含氮五元杂环酮的拟除虫菊酯. 化合物结构经¹H NMR, IR, MS和元素分析进行表征. 并用X-ray单晶衍射测定了化合物3-(1-对乙氧基-2,2-二氯环丙烷甲酰)-2-噁唑烷酮(4a-1)的晶体结构. 对合成的化合物进行了初步的生物活性测试, 结果表明, 在试验浓度下部分目标化合物对黄瓜灰霉病菌具有一定得防效作用; 其中, 化合物(4a-1)和3-(3-(2-氯-3,3,3-三氟-1-丙烯)-2,2-二甲基环丙烷甲酰)-2-噻唑烷酮(4b-3)对粘虫也分别有50%及90%的杀虫活性.     

Calix[4]Arenes in the partial cone conformation as ionophores in silver ion-selective electrodes

Two calix[4]arene derivatives, in the partial cone conformation, with sulfur-containing functionalities, were tested as neutral carrier ionophores in potentiometric silver-selective electrodes of conventional membrane and membrane-coated glassy carbon electrode types. Comparison with a calix[4]arene in the cone conformation was made. The membranes were prepared using either 2-nitrophenyl octyl ether or bis(ethylhexyl)sebacate as plasticizers and potassium tetrakis(p-chlorophenyl)borate as the lipophilic salt in a poly(vinyl chloride) matrix. Both calix[4]arenes yielded electrodes of good sensitivity (approx. 47 mV dec⁻¹) in the range 10⁻⁴–10⁻¹ M and excellent selectivity [log K_Ag,_MH+ < −1.5] of transition, alkali and heavy metal cations, including sodium, mercury(II) and lead(II) cations. Temperature effects and reproducibility of response were determined and the interfering effects of mercury(II) and lead (II) ions on the membranes were noted. The partial cone conformation allows improved selectivity over certain cations relative to calix[4]arenes in the cone conformation.     

Spectral,BVS, and Thermal Studies on Bisdithiocarbamates of Divalent Zn,Cd, and Their Adducts: Single Crystal X-Ray Structure Redetermination of (Diiodo) (Tetraethylthiuramdisulfide)mercury(II), [Hg(tetds)I2]

The current article describes the TG and DT analyses of divalent Zn, Cd, and Hg dithiocarbamato (dtc) complexes and their adducts (dchdtc = N,N-dicyclohexyldithiocarbamate anion, 4-mpzdtc = 4-methylpiperazinecarbodithioato anion, padtc = N,N′-(iminodiethylene)bisphthalimidedithiocarbamate anion, pipdtc = piperidinecarbodithioate anion, 1,10-phen = 1,10-phenanthroline, and 2,2′-bipy = 2,2′-bipyridine) along with the structural reinvestigation of [Hg(tetds)I ₂ ], where tetds = tetraethylthiuramdisulfide. In the case of Zn(II) and Cd(II) dithiocarbamates and their nitrogenous adducts, thermal decomposition of the nitrogenous bases is followed by the decay of dithiocarbamate leading to the formation of ZnS or CdS as residue. The interaction of iodine with [Hg(dedtc) ₂ ] in CHCl ₃ results in the oxidation of diethyldithiocarbamate leading to the formation of [Hg(tetds)I ₂ ], and the structure was redetermined because the earlier determination was by a Polaroid crystallographic technique with a higher R value. The S-Hg-I bond angles [105.09(3); 105.59(3); 109.26(3), and 100.99(3)°] indicate the near tetrahedral environment around the metal ion. ¹ H and ¹³ C NMR spectra of the complex were analyzed. Whether the product formed upon oxidation is a disulfide or an iodo-substituted product, in the present investigation, is clearly decided by the bulkiness of the substituent attached to the nitrogen. Interestingly, the steric influence is a deciding factor only in the case of mercury compounds and the dithiocarbamates involving Zn, Cd forms of the disulfide complexes.     

Preparation and Properties of a Representative of a New Series of Chalcogen-containing 1,5-Diketones, Di(1-oxo-1,2,3,4-tetrahydro-2-naphthyl) Sulfide

Di(1-oxo-1,2,3,4-tetrahydro-2-naphthyl) sulfide has been obtained and its behavior towards hydrogen sulfide in situ, ammonium acetate, hydrazine hydrate, and hydrogen peroxide has been studied. The structure of the compounds synthesized was established by IR and by ¹H and ¹³C NMR spectroscopy and by chromato-mass spectrometry.     

Novel mercury(II) complexes of meso-tetraphenylporphyrin and N-methylporphyrins

Treatment of meso-tetraphenylporphyrin, H₂TPP, with just over one equivalent of mercury(II) acetate in methylene chloride-THF gives mercury(II) meso-tetraphenylporphyrin, HgTPP. With excess of mercury(II) acetate, H₂TPP and HgTPP afford a novel dimetallic mononuclear porphyrin, AcOHgTPPHgOAc. In contrast, HgTPP reacts with mercury(II) chloride to give the chloro-analogue, ClHgTPPHgCl, but there is no reaction between H₂TPP and mercury(II) chloride. Demetallation of HgTPP in methylene chloride containing small amounts of hydrogen chloride proceeds via the dimetallic compound, ClHgTPPHgCl, to give free base HTPP. The reaction rate is dependent upon acid concentration suggesting that the rate determining step is protonation, but dilution causes no decrease in the rate; a mechanism which invokes the intermediacy of monohydrogen-meso-tetraphenylporphyrinatomercury(II) chloride, H(TPP)HgCl, in the formation of ClHgTPPHgCl and in its subsequent decomposition into H₂TPP, is proposed.N-Methylporphyrins react with mercury(II) acetate in methylene chloride-tetrahydrofuran to give the corresponding N-methylporphyrinatomercury(II) acetates, Me(P)HgOAc.     

Synthesis,characterization, antifungal and antibacterial activities evaluation of copper (II), zinc (II) and cadmium (II) chloride and bromide complexes with new (E)-1-(3,4-dimethoxybenzylidene)-4-methylthiosemicarbazone ligand

The reactions of Cu (II), Zn (II) and Cd (II) chloride or bromide with (E)-1-(3,4-dimethoxybenzylidene)-4-methylthiosemicarbazone (MTSVT) lead to the formation of new complexes. They were characterized by spectroscopic studies: IR, ¹H and ¹³C NMR. The crystal structures of the compounds [MTSVT] ( L ), [ZnBr₂(MTSVT)₂] ( 2 ), [CdCl₂(MTSVT)₂] ( 3 ) and [CdBr₂(MTSVT)₂^.H₂O] ( 4 ) were determined by X-ray diffraction. For complexes 2 – 4 , the ion is coordinated through the sulfur atom. All compounds were tested for their antifungal activity against human pathogenic fungi Candida albicans and Aspergillus fumigatus, and for their antibacterial activity against Gram (+) Bacillus subtilis and Enterococcus faecalis as well as against Gram (−) bacteria such as Paracoccus yeei and Acinetobacter baumanii. The results indicated that the metal complexes exhibited a marked enhancement in antibacterial activity compared with the parent Schiff base.     

Synthesis and crystal structure of bis{(μ-chloro)-chloro-[N-benzoyl-N′-(2-hydroxyethyl)thiourea] mercury(II)}

The complex bis{(µ-chloro)-chloro-[N-benzoyl-N′-(2-hydroxyethyl)thiourea] mercury(II)} was prepared by reaction of HgCl₂ with N-benzoyl-N′-(2-hydroxyethyl) thiourea(HL). The compound was characterized by IR and ¹H?NMR spectroscopy and its structure was determined by single crystal X-ray diffraction. The complex is binuclear with two Hg(II) ions tetrahedrally coordinated by a terminal chloride, two bridging chlorides and a HL molecule. The Hg(II) ion is coordinated with HL via S(1).     

Über Kupfer(I)-carboxylate und Chlorocuprate(I)

In mixtures of 7 vol. acetonitrile and 3 vol. acetic acid, solutions or suspensions of copper(II) acetate can be reduced with hydrazine hydrate to solutions of copper(I) acetate. In this way, purely white copper(I) acetate can be isolated. Other copper(I) carboxylates can be prepared by reduction of copper(II) carboxylates or by reaction of solid carboxylic acids with copper(I) acetate. By adding acetyl chloride to solutions of copper(I) acetate in acetonitrile/acetic acid mixtures, solutions of chlorocuprates(I) are formed. From these, highly pure copper(I) chloride can be obtained. By adding alkali acetate or tetramethyl ammonium chloride to solutions of chlorocuprates(I), the pure compounds Cs₃[Cu₂Cl₅], Rb₂[CuCl₃] and NMe₄[Cu₂Cl₃] were obtained.     

Transformations of mercury species in the presence of Elbe river bacteria

The influence of Elbe river bacteria isolated from suspended particulate matter (SPM) on dynamic species transformation of mercury was investigated. Experiments were carried out in the presence of bacteria (batch cultures) and in sterile tapwater as a control. For the methylation of inorganic mercury ions by bacteria several cofactors are under discussion. In this work, methylcobalamin, methyl iodide and S-adenosylmethionine were tested as biogenic methyl donors and trimethyl-lead chloride, trimethyltin chloride and dimethylarsenic acid as abiotic methyl donors. Transmethylation reactions as examples of abiotic methyl transfers have higher effectiveness in the formation of methylmercury (CH₃Hg⁺) than methylation with biogenic compounds. This result was observed in batch cultures as well as in sterile water. SPM-bacteria inhibit methyl transfer to mercury(II) ions. This is not only due to passive adsorption processes of mercury(II) to bacterial cell walls; methylmercury is also decomposed very rapidly by SPM-bacteria and is immobilized as mercury(II) by the cells.     

Unusual bridging modes for percholorate in a 2D polymeric lead(II) complex, {[Pb(bpy)(µ-OAc)]2(µ-O2ClO2)(µ-OClO2O)}n

A lead(II) complex containing 2,2′-bipyridine (bpy), acetate and perchlorate ligands, [Pb(bpy)(CH₃COO)(ClO₄)] has been synthesized and characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy. Single crystal X-ray data show the complex is two dimensional polymeric as a result of an unusual perchlorate bi- and unidentate bridging with repeating dimeric {[Pb(bpy)(µ-OAc)]₂(µ-O₂ClO₂)(µ-OClO₂O)}_n units. The Pb atom has an unsymmetrical eight-coordinate geometry with a coordination gap around the Pb(II) ion, possibly occupied possibly by a stereo-active lone pair of electrons on lead(II).     

Binary and ternary complexes involving manganese(II), 2,2’-bipyridine and halide or thiocyanate ions inN,N-dimethylformamide

Ternary complexation involving the manganese(II) ion, 2,2’-bipyridine (bipy), and halide (chloride, bromide) or pseudohalide (thiocyanate) ions has been studied by precise titration calorimetry inN,N -dimethylformamide (DMF) at 298K. All the titration curves are explained well in terms of formation of mononuclear complexes of the type [MnX_m(bipy)_n](^2-m) + (X = CI, Br or SCN), and the formation of [MnCl(bipy)]⁺, [MnCl₂(bipy)], [MnCl(bipy)₂]⁺ and [MnCl₂(bipy)₂] has been established in the chloride system, [MnBr(bipy)]⁺, [MnBr₂(bipy)], [MnBr(bipy)₂]⁺ in the bromide system, and [Mn(NCS)(bipy)]⁺, [Mn(NCS)₂(bipy)], [Mn(NCS)₃(bipy)]^-, [Mn(NCS)(bipy)₂]⁺, and [Mn(NCS)₂(bipy)₂] in the thiocyanate system. The data were analyzed on the basis of the thermodynamic parameters for the binary Mn^lIbipy and Mn^II-X (X = Cl, Br and SCN) systems, the latter being determined in previous work. The formation constants, reaction enthalpies, and entropies of the ternary complexes were extracted. The thermodynamic parameters thus obtained are discussed in comparison with those of the corresponding systems of other transition metal(II) ions.     

The crucial role of C—H...O and C=O...π interactions in the building of three‐dimensional structures of dicarboxylic acid–biimidazole compounds

The supramolecular architectures of three dicarboxylic acid–biimidazole compounds, namely, 2,2′‐biimidazolium malonate, C₆H₈N₄²⁺·C₃H₂O₄²⁻, (I), 2,2′‐bi(1H‐imidazole) succinic acid, C₆H₆N₄·C₄H₆O₄, (II), and 2,2′‐biimidazolium 2,2′‐iminiodiacetate chloride, C₆H₈N₄²⁺·C₄H₆NO₄⁻·Cl⁻, (III), are reported. The crystal structures are assembled by the same process, namely double conventional N—H...O or O—H...N hydrogen bonds link the dicarboxylates and biimidazoles to form tapes, which are stacked in parallel through lone‐pair–aromatic interactions between carbonyl O atoms and biimidazole groups and are further linked via weak C—H...O interactions. The C=O...π interactions involved in stacking the tapes in (II) and the C—H...O interactions involved in linking the tapes in (II) and (III) demonstrate the crucial role of these interactions in the crystal packing. There is crystallographically imposed symmetry in all three structures. In (I), two independent malonate anions have their central C atoms on twofold axes and two biimidazolium dications each lie about independent inversion centres; in (II), the components lie about inversion centres, while in (III), the unique cation lies about an inversion centre and the iminiodiacetate and chloride anions lie across and on a mirror plane, respectively.     

ZnII and HgII complexes of 2,2′-diamino-4,4′-bis(1,3-thiazole) (DABTZ), spectroscopic,thermal and structural studies

New zinc(II) and mercury(II) complexes of 2,2′-diamino-4,4′-bis(1,3-thiazole) (DABTZ), [M(DABTZ)(CH₃COO)₂], have been synthesized and characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy and studied by thermal analysis and X-ray crystallography. The structural characterization of the [Zn(DABTZ)(CH₃COO)₂] complex shows the complex to be a monomer and the Zn coordinated by two nitrogen atoms of the “DABTZ” ligand and four oxygen atoms of the acetate anions.     

Syntheses, structures, absorption and emission properties of a tetraiminodiphenol macrocyclic ligand and its dinuclear Zn(II) and Pb(II) complexes

Synthesis of a Robson type macrocyclic ligand [H₄L](ClO₄)₂ (1) obtained on condensation of 2,6-diformyl-4-methylphenol and 2,2′-dimethyl-1,3-diaminopropane, template synthesis of a dinuclear lead(II) complex [Pb^II₂L(NO₃)₂] (2), synthesis of a dinuclear zinc(II) complex [Zn^II₂L(NO₃)(H₂O)](ClO₄) (3) through metal substitution reaction and synthesis of another dinuclear zinc(II) complex [Zn^II₂L(H₂O)₂](ClO₄)₂·(H₂O)₂ (4) obtained directly from 1 are described in the present study. Crystal structure determinations of 1 and 3 have been carried out. Both the compounds 1 and 3 crystallize in the orthorhombic system with the space groups Fdd2 and P2₁2₁2, respectively. Spectrophotometric and spectrofluorometric titrations of 1 with triethylamine as well as with zinc(II) acetate are also reported.