Hg Molar Ratios Research Articles

Synthesis and Characterization of Cycloruthenated 2-(Phenylimino)phenyls: A Useful Probe for the Elucidation of the Tautomeric Process in 2-Hydroxyphenyl-Schiff Bases

Treatment of [RuHCl(CO)(PPh3)3] with a 1:1 molar ratio of Hg{o-C6H4C(H)NC6H4-4-R}2 in refluxing toluene afforded the new compounds [RuCl(CO){η2-C,N-C6H4C(H)NC6H4-4-R}(PPh3)2] (R = NMe2, 1a; Me, 1b; I, 1c; NO2, 1d) in good yield. The new compounds have been fully characterized by elemental analysis, IR spectroscopy, and 1H, 13C{1H}, and 31P{1H} NMR spectroscopy. A linear correlation in a Hammett plot of the metalated carbon resonance of the imine ligand versus σ+-values is observed, and this is used to comment on, along with the reported ν(CO) data and data previously reported for analogous azo-containing complexes, the keto/enol tautomerization undergone by 2-hydroxyphenyl-Schiff bases. These data suggest that the position of the tautomeric equilibrium is affected by electron-withdrawing or -releasing substituents in the same way as for the analogous 2-phenylazophenols. During the purification of 1a and 1b small amounts of the bis-cyclometalated imine-containing complexes [Ru(CO){η2-C,N-C6H4C(H)NC6H4-4-R}...

Selenium and mercury concentrations in some fish species of the Madeira River, Amazon Basin, Brazil.

Samples of 7 species of piscivorous, omnivorous, and herbivorous fish caught at 12 different sites on the Madeira River, Amazon Basin, were analyzed for selenium and mercury. Selenium was determined by anodic stripping voltammetry and mercury by cold vapor atomic absorption spectrophotometry. The means for selenium concentrations ranged from 0.49 to 3.11 nmol/g and for mercury from 0.41 to 6.66 nmol/g depending on the fish species. The molar ratios of Hg:Se increased according to the fish trophic level. Piscivorous species had the highest mean ratio (4.0) and herbivorous species the lowest (0.9). There was a positive and statistically significant correlation between selenium and mercury concentrations for the herbivorous species (r = 0.716; p = 0.0088) not seen for omnivororus and piscivorous species (r = -0.2032; p = 0.3407). These findings are significant for the fish-eating population of the Madeira River because the ingestion of mercury would always be in excess of selenium.

An investigation of the equilibrium of mercury(II) thiocyanate complexes in DMF solutions via Raman spectra and factor analysis

Using Raman spectra and factor analysis, the equilibria of mercury(II) thiocyanate complexes in N,N-dimethylformamide solutions with SCN-/Hg(II) molar ratios ranging from 0.6 to 4.0 have been investigated. The spectra were recorded in the region of the ν(Hg–S) and ν(C–N) vibrations. In the former, the Raman bands belonging to four complex species, Hg(SCN)+, Hg(SCN)2, Hg(SCN)3- and Hg(SCN)42-, have been extracted by applying principal component analysis to the spectra. Three components were found in the ν(C–N) region. The concentration of the identified complex species in all investigated solutions has been determined by a target factor analysis method and the disproportionation constants of Hg(SCN)+ and Hg(SCN)3- have been estimated to be 0.18 and 0.21, respectively.

Interaction of alkylmercuric compounds with sodium selenite. III. Biotransformation, levels of metallothioneinlike proteins and endogenous copper in some tissues of rats exposed to methyl or ethylmercuric chloride with and without sodium selenite.

The biotransformation efficiency of alkylmercurial compounds was studied in rat liver, kidneys, blood, and brain after 2-week administration of methylmercuric chloride (MeHg) and ethylmercuric chloride (EtHg) at doses of 0.25 or 2.5 mg Hg/kg, alone or in combination with sodium selenite (Se) at a level of 0.5 mg Se/kg. Simultaneously, the level of metallothioneinlike proteins (MTP) and endogenous copper (Cu) was monitored in tissues of control rats and intoxicated rats. Regardless of the dose, the highest concentrations of inorganic mercury from both the alkylmercurials was found in the rat kidneys. Sodium selenite had a variable effect on the amount of inorganic mercury liberated, depending on the organ and the molar ratio of Hg:Se administered. A statistically significant increase in the levels of MTP and endogenous Cu, compared with control group, was found only in the kidneys of intoxicated rats. This increase was dependent on the concentration of inorganic mercury liberated by biotransformation of alkylmercurials. The observed changes appeared when the level of inorganic mercury exceeded 10 micrograms Hg/g tissue and reached a plateau at about 40 micrograms Hg/g tissue. In the presence of selenium the plateau of MTP and Cu levels were no observed in the kidneys, regardless of the amount of inorganic mercury liberated.

Interaction of alkylmercuric compounds with sodium selenite. III. Biotransformation, levels of metallothioneinlike proteins and endogenous copper in some tissues of rats exposed to methyl or ethylmercuric chloride with and without sodium selenite

The biotransformation efficiency of alkylmercurial compounds was studied in rat liver, kidneys, blood, and brain after 2-week administration of methylmercuric chloride (MeHg) and ethylmercuric chloride (EtHg) at doses of 0.25 or 2.5 mg Hg/kg, alone or in combination with sodium selenite (Se) at a level of 0.5 mg Se/kg. Simultaneously, the level of metallothioneinlike proteins (MTP) and endogenous copper (Cu) was monitored in tissues of control rats and intoxicated rats. Regardless of the dose, the highest concentrations of inorganic mercury from both the alkylmercurials was found in the rat kidneys. Sodium selenite had a variable effect on the amount of inorganic mercury liberated, depending on the organ and the molar ratio of Hg:Se administered. A statistically significant increase in the levels of MTP and endogenous Cu, compared with control group, was found only in the kidneys of intoxicated rats. This increase was dependent on the concentration of inorganic mercury liberated by biotransformation of alkylmercurials. The observed changes appeared when the level of inorganic mercury exceeded 10 micrograms Hg/g tissue and reached a plateau at about 40 micrograms Hg/g tissue. In the presence of selenium the plateau of MTP and Cu levels were no observed in the kidneys, regardless of the amount of inorganic mercury liberated.

Interaction of poly(2-vinyl pyridine 1-oxide) with mercuric ions

The interaction of poly(2-vinylpyridine 1-oxide) with mercuric chloride forms a stable chelate with mercuric ions in contrast to the monomer analogue 2-methylpyridine 1-oxide. Conductivity and u.v. measurements showed that chloride ions are not involved in the chelate formation and that the molar ratio of Hg 2+ to the oxide is 1 to 2 in excess mercuric chloride. Viscosity measurements suggest that the chelate is a polyelectrolyte and is formed in both neutral and acid solution. 0.2% HgCl 2 causes a remarkable drop in the viscosity of 0.4% polymer solution whereas a similar concentration of CaCl 2 has no effect. Temperature change from 27–45°C has little effect on the stability of the chelate. The possible use of this polymer for removing mercuric ions from aqueous solution is discussed.

Effect of mercuric and silver ions on cesium sulfate equilibrium buoyant densities of synthetic polydeoxyribonucleotides

The effect of Hg 2+ and Ag + on the buoyant density (ϱ) of four synthetic DNA polymers, poly[d(A-T)]; poly(dA) · poly(dT); poly[d(G-C)]; and poly(dG) · poly(dC), was investigated. The buoyant density of poly[d(A-T)] in Cs 2SO 4 increased dramatically after complexing with Hg 2+, but little change in the buoyant density of other polymers resulted except at very high molar ratios of Hg 2+ DNA-P ( r f) Hg 2+ raised the thermal transition temperature ( T m) of alternating polymers and lowered the T m of homopolymers. Measurements in the preparative ultracentrifuge indicated that lowered T m correlated with Hg 2+-induced strand separation of one homopolymer [poly(dA) · poly(dT)], but strand separation was not observed with another homopolymer [poly(dG) · poly(dC)] complexed with Hg 2+. When Ag + was mixed with the polymers, the buoyant density of poly(dG) · poly(dC) increased most markedly. A substantial increase in the buoyant density of poly[d(A-T)] and a small increase in the buoyant density of poly[d(G-C)] were also observed. The T m changes induced by Ag + were not related in any obvious way to buoyant density changes. These findings indicate that nucleotide sequence as well as overall base composition is of importance in understanding the buoyant density changes induced by metal ions. Although these data do not allow construction of a detailed molecular model of polymer-metal ion interactions, they may be used to explain much of the behavior of naturally occurring DNA sequences, such as heterochromatic satellite sequences and 5 S and rRNA sequences, in Hg 2+/Cs 2SO 4 and Ag +/Cs 2SO 4 gradients.