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Presently, there is increased attention and focus on heavy metals, which are becoming one of the most serious environmental problems due to their adverse health effects. These toxic heavy metals are not easily degraded and require removal from polluted water to protect people and the environment. The purpose of this work was to prepare two types of dithiocarbamate ligands, one aliphatic (diethyldithiocarbamate) and the other aromatic (diphenyldithiocarbamate), and to use them as chelators to remove Pb, Cd, Cu and Zn from polluted water. Dithiocarbamates were selected because they have good binding ability and can precipitate metal ions as complexes.The metal removal efficiency is compared between both ligands and also compared to the efficiency of activated carbon in an adsorption process to remove the same metals.The investigation results indicated that the diphenyldithiocarbamate ligand was more efficient in removing the studied metals than the diethyldithiocarbamate analogues.Additionally, the metal removal efficiency of the diphenyldithiocarbamate ligand was more effective than using the activated carbon method.

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The complexes 3a -p were prepared from disubstituted cyanamides and Lewis acids. According to a X-ray structural analysis, the antimony pentachloride complex 3 s is neither a a nor a n complex (9: C = N -S b 133"). The complexes 3 with SbCI, and FeCI, can be alkylated with tertiary alkyl chlorides, affording crystalline cyanamidium salts (5a -m) which were characterized by reactions with water, primary or secondary alcohols to give ureas (11) and uronium salts (8a-z), respectively. The guanidinium salts 9 a -s were obtained with ammonia, primary and secondary amines. Metallkomplexe von Cyanamiden und ihre Alkylierung zu Cyanamidiumsalzen. Eine ailgemeine Synthese hochsubstituierter Harnstoffe, lsoharnstoffe und GuanidineAus disubstituierten Cyanamiden und Lewis-Sauren werden die Komplexe 3a -p erhalten. Nach einer Rdntgenstrukturanalyse hat der Antimonpentachlorid-Komplex 3a weder a-noch n-Symmerrie ( 9: C = N -Sb 133 "). Die Komplexe 3 mit SbCI, oder FeCI, kdnnen mit tertiaren Alkylchloriden zu den kristallinen Cyanamidiumsalzen 5 a -m alkyliert werden. Mit Wasser, primaren oder sekundaren Alkoholen reagieren die Verbindungen 5 zu Harnstoffen (11) bzw.Uroniumsalzen (8a -z), mit Ammoniak, primaren oder sekundaren Aminen zu Guanidiniumsalzen (9a -s).Disubstituted cyanamides react with many metal centres to form stable complexes.There have to be considered three sites at a cyanamide to which the metal may be coordinated: a lone pair of electrons at each nitrogen and the nitrile n-electrons. The spectral properties of the known cyanamide complexes seem to be consistent with coordination to the nitrile group only. Usually, an increase in the energy of the nitrile antisymmetric stretching vibration (e.g. dimethylcyanamide: vCN = 2221 cm-'; 0.1 M in CCI,')) on complexation is taken as evidence for a coordination to the nitrile lone pair (a complex) (e.g. (CH3),NCN.BF3: vCN = 2307 cm-'; 0.1 M in CCI,')), while a shift to smaller wave numbers is believed to demonstrate complexation to the nitrile n system (n complex) (e.g. 1: vCN = 2008 cm-'; KBr2)). The Cr(0) complex 2 of diethylcyanamide has been shown by an X-ray structural analysis to be a a complex3). Similar complexes with other transition metals are known4vS). On the other hand, in the nitrile complex 16) and related compounds7~*) the nitrile group acts as a four electron donor forming a a bond to one metal atom and a A bond to an other. In such cases there is no simple relation between the position of va in the IR spectra and the structure of the cyanamide complex. Therefore, the classifi-0