Nickel dithiocarbamate complexes

The nickel(II) dithiocarbamate complexes are neutral, water-insoluble, usually square-planar, species, and they have been studied extensively by a range of physical techniques. The usual methods for the synthesis of dithiocarbamate complexes have been employed in the case of Ni(II), Pd(II), and Pt(II). In addition, McCormick and co-workers (330,332) found that CS2 inserted into the Ni-N bonds of [Ni(aziri-dine)4P+, [Nilaziridinelgf, and [Ni(2-methylaziridine)4] to afford dithiocarbamate complexes. The diamagnetic products are probably planar, but they have properties typical of dithiocarbamate complexes, and IR- and electronic-spectral measurements suggested that they may be examples of N,S-, rather than S,S-, bonded dithiocarbamates. The S,S-bonded complexes are however, obtained, by a slow rearrangement in methanol. The optically active lV-alkyl-iV(a-phenethyl)dithio-carbamates of Ni(II), Pd(II), and Cu(II) (XXIV) have been synthesized, and the optical activity was found to be related to the anisotropy of the charge-transfer transitions (332). 

Until now the coordination chemistry of nickel(H) complexes with sulfur donors has been dominated by the dithiocarbamate and phosphorodithioate complexes since they are generally easy to prepare, and a wide range of substituents can be introduced in these ligands. Recently, complexes with simple ligands such as S2-, S ", HS and RS- have also been characterized and investigated. 

Nickel(II) complexes with either bidentate mononegative ligands, such as dithiocarbamates, phosphorodithioates and thiocarboxylates, or monodentate neutral and anionic ligands are generally square planar. Nickel(II) complexes with Se and Te donors are strictly similar to those with S donors. 

Substituted dithioformate anions as ligands R C(S)S are usually called dithiocarbamates (R = R2N), alkyl and aryl dithiocarbonates or xanthates (R = RO), alkyl and aryl trithiocar-bonates or thioxanthates (R = RS). Dithioacid anions (R = alkyl, aryl) have been rarely used as ligands of nickel(II) because of their instability. Structural properties of selected nickel(II) complexes with substituted dithioformate, dithiolene and related ligands are shown in Table 90. 

Nickel(III) complexes with dithiocarbamates are still rare, the best examples being Ni(Et2dtc)3 and Ni(Bu2dtc)2I. Ni(Et2dtc)3 has been prepared by oxidation of Ni(Et2dtc)2 with... 

Nickel(IV) complexes with dithiocarbamates are more stable than the nickel(III) ones. Complexes of formula [Ni(R2dtc)3]X (R = Et, Bu X = Br, I) are generally prepared by halogen oxidation of the parent nickel(II) complexes at room temperature.3227-3229... 

Standard official methods have been described for the determination of nitric-perchloric acid-soluble nickel [174] and acetic acid-extractable nickel [175] in soil. To determine nitric acid-perchloric acid-soluble nickel [174], the acid digest is dissolved in hydrochloric acid and the nickel is determined by atomic absorption spectrometry. To determine extractable nickel, the nickel is first extracted from the soil with 0.5 M acetic acid and the nickel is then converted to the ammonium pyrrolidine dithiocarbamate complex. Extraction of the complex with chloroform provides an extract for the determination of nickel by atomic absorption spectrometry. 

Thiomorpholin-3-one forms Cu(tm)2X2 (X = Cl, Br, or I), Cu2(tm)2(S04)2 and [Cu(tm)4](N03)2 which are probably S-bonded in contrast to the O-bonding found in the nickel(n) complexes.602 Diethanol dithiocarbamic acid forms Cu[(HOC2H4)2-NCS2]2 which is a monomeric planar CuS4 chromophore in solution, but Cu - S interaction probably occurs between neighbouring molecules in the solid state.603... 

The crystal structure of bis(NN-di-isobutyldithiocarbamato)nickel(ii). [Ni(S2-CNBu 2)2], shows that nickel is approximately square planar and co-ordinated by two symmetric bidentate ligands (Ni—S = 2.20 A) the ligand symmetry approximates to 2- The reduction mechanism of a series of nickel(ii) dithiocarbamates has been investigated in DMSO at the mercury electrode it is claimed to involve a dissociation to a nickel species which is more easily reduced than the nickel(ii) dithiocarbamate. An e.p.r. study of the reversible electrochemical reduction of nickel(ii) diethyldithio-carbamates in the presence of 2,2 -bipyridyl show that a bipy radical anion is formed initially. Ligand alkylation occurs when ao -dibromo-o-xylene is added to bis-(NiV-diethyldithiocarbamato)nickel(ii). The electron-transfer properties of 16 nickel(ii) dithiocarbamate complexes have been studied in acetone at a platinum electrode. Their oxidation is difficult and irreversible the overall process is ... 

Atsuya I, Itoh K, Ariu K. 1991. Preconcentration by coprecipitation of lead and selenium with nickel-pyrrolidine dithiocarbamate complex and their simultaneous determination by internal standard atomic absorption spectrometry with the solid sampling technique. Pure Appl Chem 63(9) 1221-1226. 

Intra- and Intermolecular Rearrangements. Pignolet and cO-workers (44) described a variety of intramolecular rearrangements of the tris (dithiocarbamates) and suggested that with iron (II) as the metal ion the process involves a trigonal prismatic intermediate. With the nickel (IV) complex, only a broad PMR spectrum was observed with no resolution... 

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