Dithiocarbamate iron complexes

The formation of the highly reactive superoxide radical ion (Oj ) explains the exceptional photoactivating effect of iron dithiocarbamate in polyethylene degraded in air [124]. 

The disulphide radical (thiyl radical, xantogen radical) (5.5) can abstract hydrogen from a polymer molecule (PH) and in this way produce a polymer alkyl radical (P ), which is susceptible to oxidation to form a polymer 

Iron dithiocarbamate is an important additive for producing photodegrad-able polyolefins which have time-controlled decay of their mechanical properties [116,124,1917,1920]. Their potential uses range from very shortlived materials such as packaging which is required to degrade in the environment immediately it is discarded, through protective films for annual crops, where a lifetime of several months is required, to a protective mulch for young trees, which may be required to stand up to 3-4 years in exposed environments before embrittlement. 

Outdoor exposure tests performed on commercial photodegradable polyethylene (LDPE) packaging based on iron dithiocarbamate have shown that fragmentation occurs under the influence of wind and weather when the elongation at break is reduced to about 20% of the original value (Fig. 5.16). In polyethylene (HOPE), particularly in thick samples, iron dithiocarbamate 

On the other hand, dithiocarbamate nickel and zinc complexes are very effective light stabilizers for polyolefins. Using a combination of iron(pro-oxidant) and nickel or zinc (stabilizers) dithiocarbamates, it is possible to control the rate of photo-oxidative degradation very accurately [1931]. For long induction periods a combination of iron and nickel dithiocarbamates is recommended, whereas for shorter times it is more usual to combine iron and zinc dithiocarbamates [1932]. The combination of different metal ions decreases the induction period and increases the rate of photo-oxidation. At higher concentrations of stabilizing (Ni, Zn) dithiocarbamates, much longer lifetimes can be achieved. 

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Trivalent iron dithiocarbamate complexes have been extensively studied, because of the existence of "spin equilibria in these complexes. Table II outlines the tris(l,l-dithiocarbamate) iron(III) complexes and, some of their physical properties. 

The traditional copper fungicides are in fact inorganic copper coordination compounds The still most important group of organic protectant fungicides, the dithiocarbamates, are applied in the form of their metal-coordination compounds. Dimethyldithiocarbamate as the iron complex ferbam and the zinc complex ziram, ethylenebisthiocarbamate as the zinc complex zineb and the manganese complex maneb. 

SYNONYMS carbamate, dimethylcarbamodithioic acid, iron complex, ferric dimethyl-dithiocarbamate, iron dimethyldithiocarbamate, iron tris (dimethyldithiocarbamate), karbam... 

Iridium(V) complexes, 1158 fluorides, 1158 Iridium(VI) complexes, 1158 Iron complexes acetonitrile, 1210 analysis, 1180, biological systems, 1180 coordination geometries, 1183 coordination numbers, 1182-1187 dinitrosyldicarbonyl, 1188 Mdssbauer spectroscopy, 1181 nitric oxide, 1187-1195 nitrosyls binary, 1188 bis(dithiolene), 1193 carbonyl, 1188 dithiocarbamates, 1192 halides, 1193 iodide, 1193... 

Vinyl acetate is the monomer that has required significant efforts in order to achieve LRP. The first successfiil attempt was using RAFT with xanthates as a RAFT agent (also known as MADIX). At a later stage it turned out that certain dithiocarbamates also were able to induce LRP of vinyl acetate. Of all the attempts to pol5unerize VAc using ATRP, only specific iron complexes used by Sawamoto and co-workers were claimed to be successful (61). However, the PDIs they claimed were relatively large compared to other monomer/catalyst combinations. 

In this paper we shall extend our earlier interpretation of the redox results to the nmr data for the N - CH2 protons in tris(N,N-diethyldithiocarbamato) iron(III). We shall show that the solvent dependence of the nmr shifts can be interpreted as arising from solvent interactions with the iron(III) dithiocarbamate system. Although the solvent interactions are small compared with the electronic interactions within the transition metal iron complex the effect is marked since in these cases for the d iron system there are low lying electronic states where the energy separation is sensitive to small changes in the crystal field environment of the transition metal ion. 

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