Mercury complexes dithiocarbamates

Mercury Mercury complexed with ammonium tetra methylene- Chloroform extract analysed by < 5 ng/1 Hg absolute dithiocarbamate, extracted with chloroform graphite tube AAS... 

The solid sample is placed in the preheated extraction thimble, and the modified CO2 is added to the desired extraction pressure. The system is held static at the extraction temperature and pressure. At the end of the period, the system is vented into a collection vial containing chloroform. This is followed by a dynamic flush of the system with the CO2 solvent at the same temperature and pressure. Mercury complexed with fluorinated diethyl-dithiocarbamate was extracted from dried aquatic plant material with 95% efficiency by methanol-modified CO2. 

Dithiocarbamates and thioureas are included in this section because of their useful electrochemical behavior at mercury and mercury amalgam electrodes. The formation of mercury complexes results in an easy oxidation at the mercury electrode. On the other hand, carbon electrodes are not well suited for the detection of these compounds because the oxidation occurs beyond the usual scope of carbon detector cells. 

Berman (1967) complexed mercury with ammonium pyrrolidine dithiocarbamate (APDC) in urine, blood, and other tissue samples treated with trichloroacetic acid. She extracted the complex into methylisobutyl ketone (MIBK), and reported a detection limit of about 10 /complexed with APDC, can be quantitively extracted into MIBK from hydrochloric acid (at least up to 6 M) and nitric acid (up to 1.5 M) solutions (Brooks et al., 1989). 

Gabard B (1976) Improvement of oral chelation treatment of methyl mercury poisoning in rats. Acta Pharmacol Toxicol (Copenh) 39 250-255 Gale GR, Smith AB, Atkins LM, Jones MM (1985) Effects of diethyldithiocarbamate and N-methyl-N-dithiocarboxyglucamine on murine hepatic cadmium metallothionein in vitro. Res Commun Chem Pathol Pharmacol 49 423-434 Gale GR, Smith AB, Jones MM, Singh PK (1992) Evidence of active transport of cadmium complexing dithiocarbamates into renal and hepatic cells in vivo. Pharmacol Toxicol 71 452-456... 

By using electrochemical methods, Bond and Schultz (606) also derived a considerable number of stability constants (P2) for mercury bis(dithiocarbamate) complexes in water (Eq. 48). They found no correlation between them and the Taft substituent constants for the dithiocarbamate substituents. There is, however, a linear correlation between log p2 and the molecular weight (Mw) of the complexes, which can be represented by the empirical equation log P2 = 29.95 + 0.03301... 

Bond and Scholz (606) calculated thermodynamic data for solid mercury bis(dithiocarbamate) complexes mechanically attached to the surface of a paraffin-impregnated graphite electrode. Two-electron reduction generates mercury and the soluble dithiocarbamate anions in a chemically reversible couple during the second and subsequent scans. The formal potential of the reaction has been measured, which enables the calculation of conventional stability constants (P2) for 17 mercury complexes, and a previously unrecognized correlation between log p2 and molecular weight is found (see Section III.G). 

Figure 277. Examples of heterometallic mercury-molybdenum dithiocarbamate complexes...

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... 

The structural chemistry of some metal dithiocarbamates, i.e. systematics, coordination modes, crystal packing, and supramolecular self-assembly patterns of nickel, zinc, cadmium, mercury,363 organotin,364 and tellurium,365 366 complexes has been thoroughly analyzed and discussed in detail. Supramolecular self-assembly frequently occurs in non-transition heavier soft metal dithiocarbamates. Thus, lead(II),367 bismuth(III)368 zinc,369 cadmium,370 and (organo)mercury371 dithiocarbamates are associated through M- S secondary bonds, to form either dimeric supermolecules or chain-like supramolecular arrays. The arsenic(III)372 and antimony(III)373 dithiocarbamates are... 

Shih and Carr [277,278] showed that metal complexes of bis(/ -butyl-2-naphthyl-methyldithiocarbamate) are thermodynamically stable and chemically inert and that the nickel(II), iron(III), copper(II) and mercury (II) complexes of this dithiocarbamate can be separated by high performance liquid chromatography and detected with a variable wavelength detector. 

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