Cadmium, dithiocarbamate complexes

Cadmium Extraction of ammonium pyrrolidine dithiocarbamate complex with chloroform AAS 0.0006 xg/l [134,863]... 

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. 

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. 

The simultaneous determination of cobalt and nickel in aqueous solutions as trifluoroethyl dithiocarbamate complexes is possible down to 10 ppb in the presence of a 10-fold excess of iron, copper, cadmium, and zinc (1434), while the same dithiocarbamate is used for the determination of cobalt in urine samples by GC and MS (1435). 

Figure 257. Solid-state conformations adopted by cadmium bis(dithiocarbamate) complexes.

Both 2,2 -bpy, 1,10-phen, and their derivatives bind to both zinc (551, 591, 1158, 1906-1909, 1914, 1918, 1919, 1923, 1936-1939) and cadmium (1924-1930) in a bidentate manner leading to the generation of six-coordinate centers, with a distorted octahedral geometry. An elongation of the zinc-sulfur bonds by 0.2 A when compared to simple bis(dithiocarbamate) complexes is probably due to steric rather than electronic factors (1906), although binding of the base does result in an increase of electron density on zinc as shown by electrochemical and XPS studies (551, 552). 

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