Mercury silver complexes

There is often a need to monitor cyanide in air, water, solid waste, food, and other environmental samples. The cyanide present in these samples may include free (noncomplexed) cyanide such as hydrogen cyanide (or hydrocyanic acid in water solution), cyanogen (C2N2), cyanogen chloride, cyanide salts, or complexed cyanide such as metal-cyanide complexes of iron, nickel, copper, mercury, silver. Complexed cyanides are less toxic because they are less bioavail-able, but they may break down producing free cyanide, for example, as a result of the ultraviolet radiation in daylight. Analytical techniques for free... 

Other transition metals have received much less attention. Complexes of palladium and 2-amino-phenyl-containing formazans have been reported.397 Mercury complexes of tridentate formazans have been studied.398 Silver complexes of tridentate benzothiazolyl-containing formazans have also been studied.399 Recently, alkali and alkaline earth metals have been the subject of many studies. Formazans such as 228 and 229 as well as the macrocyclic 204 have received considerable attention as metal-specific analytical reagents.400-41 1... 

Nitroguanidine is difficult to detonate, but its mercury and silver complex salts are much more impact-sensitive [1]. Many nitroguanidine derivatives have been considered as explosives [2]. 

Transition metal carbodiimides, such as MnNCN and CuNCN, and carbodiimides derived from zinc, mercury,silver and thallium are also known. A preceramic polymeric titanium carbodiimide is obtained in the reaction of TiCU with bis(trimethyl-silyl)carbodiimide. Liganded carbodiimidotitanium complexes are obtained in the reaction of CpaTiCla with Me3SnN=C=NSi(i-Pr)3. ° Also, dicyclopentadienyl titanium (IV) diisocyanates are converted into carbodiimides with LiN(SrMe3)2. ... 

Many dithiocarbamate complexes of zinc, silver, cadmium or mercury improve emulsion stability, including bis(dibenzyldithiocarbamato)-zinc(II) or -cadmium(II) and silver(I) diethyldi-thiocarbamate. Cadmium salts, mixed with citric acid or tartaric acid and added to the emulsion, are reported to be effective. Mercury(II) complexes of ethylenediaminetetraacetic acid (EDTA) and related ligands and of solubilized thiols such as (4) can be used. Other coordination compounds reported include EDTA and related ligand complexes of Co and Mn, mixtures of Co salts with penicillamine (5) and macrocyclic complexes of Ag such as (6). The latter compounds may be used in diffusion transfer systems in which transferred maximum densities are stabilized. 

A non-dependence of the thermodynamic equilibrium constant on the solvent for two different types of diols was found 34>, which indicated that Ag+ as well as undissociated AgN03 formed complexes with olefins, comparable with mercury salt-olefin complexes 35>. Further formation constant investigations 36> by gas chromatography of silver complexes of cyclo-olefins had shown that methyl substitution at the double bond markedly reduced the stability and... 

Cadmimn, copper, mercury, silver, and tin form white precipitates with thiourea when present in high concentrations. Only antimony(III) (and vanadate) gives a weak yellow color with thiourea. Hg, SeOj and SeO " are reduced and interfere by forming colored complexes and precipitates. ... 

H NMR spectra (DMSO-dg) of the Ag" complexes of ruthenocenophanes (81) and (82) suggest no interaction between the ruthenium and the complexed silver ion. In this case, the methylene protons attached to sulfur atoms were shifted more than the protons of the ruthenocene nucleus. H NMR spectra of the mercury(II) complexes of (80)-(82) suggest that there is signihcant interaction between ruthenium and the mercury(II). The P protons of the Cp rings were shifted further downfield than the a protons, and the ethylene protons exhibited very little downfield shift <85BCJ3540>. 

Another novel system is presented in Figure 5.9 . This is a crystalline cubic phase formed with monoolein and Myverol . This structure was used to host [Ni (cyclam)] + or the derivative l-hexadecyl-1,4,8,111 tetraaza-cyclotetradecane. After obtaining a mixture of the lipids and the catalyst, the mixture was spread over a glassy carbon electrode or a thin mercury silver film. The best catalyst for the reaction was the substituted complex because the hydrophilic [Ni(cyclam)] + is easily removed from the cubic phase. The voltam-metric results indicate that the best response is obtained on the thin mercury film with formation of CO and regeneration of the catalyst. A further reaction of [Ni(cyclam)] + in the presence of CO generates [Ni(cyclam)CO]. 

Methyl vinyl ketone is synthesized industrially by the hydration of vinylacetylene. The reaction is catalyzed by acetates, formates, or sulfates of mercury, silver, cadmium, copper, or zinc in the presence of acids [329,330]. The oxidation of 1-butene to methyl vinyl ketone in 72% yield by the formation of olefin mercuric salt complexes followed by the decomposition of these complexes with acid may become commercially feasible [331]. 

Most protein molecules, then, have many points where complexes may be formed with metals. Among these metals it is worthwhile to distinguish those which appear to be coordinated strongly and by many different polar side-chains such are mercury, silver, copper and zinc. The alkaline earth metals, like calcium, seem to be bound primarily by free carboxyl groups, or, in the phosphoproteins such as casein, by phosphate groups. 

Silver sulfadiazene is a characterized silver complex used as an antibacterial in the treatment of burns. The polymeric aggregation of the material renders it almost insoluble in water but allows for slow release of the active silver ion. Mercury salts, probably acting by non-specific thiol binding, have been known to be bacteriostatic for many years and were of undoubted chemotherapeutic utility in earlier centuries. 

Other azides do not have significant importance for practical applications. Most of them are moisture sensitive hygroscopic solids and some of them hydrolytically decompose. They also easily form complex compounds. Azides other than those of lead, copper, mercury, silver, palladium, and thallium are soluble in water and their isolation from aqueous solutions by crystallization is problematic on an industrial scale. 

The mechanism of 1 1 complex formation between palladium(II) and catechol and 4-methylcatechol has been studied in acidic media, and the rate of 1 1 (and 1 2) complex formation between silver(II) and several diols is an order of magnitude higher in basic solution than in acidic. The kinetics of formation and dissociation of the complex between cop-per(II) and cryptand (2,2,1) in aqueous DMSO have been measured and the dissociation rate constant, in particular, found to be strongly dependent upon water concentration. The kinetics of the formation of the zinc(II) and mercury(II) complexes of 2-methyl-2-(2-pyridyl)thiazolidine have been measured, as they have for the metal exchange reaction between Cu " and the nitrilotriacetate complexes of cobalt(II) and lead(II). Two pathways are observed for ligand transfer between Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II) and their dithiocarbamate complexes in DMSO the first involves dissociation of the ligand from the complex followed by substitution at the metal ion, while the second involves direct electrophilic attack by the metal ion on the dithiocarbamate complex. As expected, the relative importance of the pathways depends on the stability of the complex and the lability and electrophilic character of the metal ion. 

The most widely used titrant for such determinations is diamino-ethane-tetra-acetic acid (ethylenediamine tetra-acetic acid) which is conveniently employed as the disodium salt, referred to throughout this book as EDTA. (The titrant is referred to in the B,P, and B,P,C, as sodium edetate, but this synonym has not gained universal acceptance.) Many other amino-polycarboxylic acids have been used and in certain special applications they may have some advantage for routine pharmaceutical work, however, it has not been found necessary to use any titrant other than EDTA. This substance reacts stoichiometrically with most metals to form a 1 1 complex and, usually, the reaction is instantaneous (but see Aluminium, p. 32). pH has a marked effect on the stability of the complexes formed the alkaline earth metals form complexes that are stable in alkaline solution but decompose in neutral and acid solution aluminium, copper, lead and mercury all complex under mildly acid conditions while bismuth and ferric iron form stable complexes in a solution as acid as pH 1. The monovalent ions of sodium, potassium and silver form complexes that are too weak to be used for titration purposes whilst mercurous mercury forms no complex,... 

It is not clear when dithiocarbamates were first prepared, but certainly they have been known for at least 150 years, since as early as 1850 Debus reported the synthesis of dithiocarbamic acids (1). The first synthesis of a transition metal dithiocarbamate complex is also unclear, however, in a seminal paper in 1907, Delepine (2) reported on the synthesis of a range of aliphatic dithiocarbamates and also the salts of di-iTo-butyldithiocarbamate with transition metals including chromium, molybdenum, iron, manganese, cobalt, nickel, copper, zinc, platinum, cadmium, mercury, silver, and gold. He also noted that while dithiocarbamate salts of the alkali and alkali earth elements were water soluble, those of the transition metals and also the p-block metals and lanthanides were precipitated from water, to give salts soluble in ether and chloroform, and even in some cases, in benzene and carbon disulfide. 

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