Copper dithiocarbamate ligands

Many other sulfur compounds exhibit dimerisation reactions of this type in the presence of metal ions and oxygen. For example, dithiocarbamates are readily oxidised to the disulfides in the presence of copper salts (Fig. 9-13). Very often, attempts to form complexes with dithiocarbamate ligands are complicated by the parallel oxidation process. 

Treatment of Z>fr(butylaminomethyl)biphenyl, other spacers were also used, with CS2 and base generated the Z>fr(dithiocarbamate) ligand (dtc), which with Cu(OAc)2 generated the binuclear copper(ll) dtc macrocycle, then subsequent reaction with NaAuCU gave the novel heteropolymetallic Cu(ll)-Au(lll) catenane <05CC2214>. 

The solubilities of chelates with palladium, rhodium, lead and copper have been measured with static and dynamic spectroscopic methods at different temperatures and different pressures. The influence of different ligands, ligand modifications and of the metal ions coordination sphere on the solubility were studied and compared to the influence of pressure and temperature of the supercritical carbon dioxide (scCOa). In a series of C2, C4, Ce, Cg copper dithiocarbamates a maximum solubility was measured with the butyl substituents. 

Table 1 Solubility Parameters of Dithiocarbamate Ligands and Solubilities of Their Copper Complexes in Supercritical CO2 at 60 C and 230 atm...

Addition of aliphatic amines (L) to [Cu(S2CNEt2)2] has been studied by ESR spectroscopy (1697). Initial formation of five-coordinate adducts is proposed, while over longer periods addition of more base affords complexes of the type [Cu(S2CNEt2)2L2], which are believed to contain four coordinate, square-planar, copper centers, with a trans disposition of monodentate dithiocarbamate ligands. 

Copper(n) bis(dithiocarbamate) groups have been bound to macroporous polystyrene resins (139,1763) and other polymeric sorbents (1764), with ESR spectroscopy being used to detected and probe the nature of the copper environment. The A -sulfonylethylene bis(dithiocarbamate) ligand when anchored on macroporous polystyrene-divinylbenzene beads has been used for the selective removal of mercury(II), silver(I), and copper(II) from aqueous solutions, the overall selectivity being... 

In related work, Nomura et al. (1774,1775) prepared bimetallic copper-indium complexes, such as [Bu3 InCu(S—/-Pr) (S2CNR2)] (R = /-Pr, Bu) from the reactions of [Bu In(S—/-Pr)3 ] with [Cu(S2CNR2)2l copper(Il) was reduced to copper(I) in the process. The precise structures of these heterobime-tallic complexes are unknown, but they are believed to have bridging thiolate and dithiocarbamate ligands. Importantly, they have been utilized toward the... 

Various spectroscopic methods have been used to probe the nature of the copper centers in the members of the blue copper oxidase family of proteins (e.g. see ref. 13). Prior to the X-ray determination of the structure of ascorbate oxidase in 1989, similarities in the EPR and UV-vis absorption spectra for the blue multi-copper oxidases including laccase and ceruloplasmin had been observed [14] and a number of general conclusions made for the copper centers in ceruloplasmin as shown in Table 1 [13,15]. It was known that six copper atoms were nondialyzable and not available to chelation directly by dithiocarbamate and these coppers were assumed to be tightly bound and/or buried in the protein. Two of the coppers have absorbance maxima around 610 nm and these were interpreted as blue type I coppers with cysteine and histidine ligands, and responsible for the pronounced color of the protein. However, they are not equivalent and one of them, thought to be involved in enzymatic activity, is reduced and reoxidized at a faster rate than the second (e.g. see ref. 16). There was general concurrence that there are two type HI... 

Although transesterification and transamidation reactions of simple carbonyl ligands are usually associated with the involvement of a co-ordinated nucleophile, there are some well-documented processes which unambiguously involve attack by an external nucleophile upon a co-ordinated electrophile. Dithiocarbamate complexes contain a chelated. S, 5"-bonded dithioamide ligand and undergo facile transamination reactions upon treatment of the copper complexes with amines (Fig. 3-22). 

The self-assembly of ligands based on a pyrrole framework possessing dithiocarbamate end groups when treated with zinc(II), nickel(II) or copper(II) afforded a series of neutral, dinuclear metallomacrocycles or trinuclear metallocryptands 45 <03DT603>. 

Very often it is possible that oxidation-reduction reactions occur between the copper chelate complex and the base as a result the chelate ligands are removed from the first coordination sphere and new complexes showing catalytic activity are obtained. Similar oxidation-reduction reactions were established in the reaction of acetylacetonate, oxine, thioxine, dithiocarbamate, dithiophosphate, etc., complexes with strong Lewis bases, such as triphenylphosphine (10), piperidine, pirrolidine(ll), ammonia(6,12) etc. 

Thus the results from the studies of copper bis-dithiocarbamate complex reactions with tin(22) antimony(22) and copper(23) halides show formation of copper(II) mixed-ligand complexes. 

The potassium dithiocarbamate salt generated from 3,5-dimethylpyrazole has been reported (339) and used to prepare copper (339-341) and nickel (342) complexes. In theory, the ligand can bind in two ways, 41 and 42 (Fig. 45). A crystallographic study on 43 (Fig. 45) reveals that the ligand binds not through... 

Both Bruce (1485) and Hoshino-Miyajima (1486) and co-workers prepared bis(dithiocarbamate) complexes with long-chain substituents as potential liquid crystals. Most are derived from four-substituted piperazines with flexible alkoxy tails (345), and are mesomorphic, showing smectic phases Sc and crystal B mesophases (1485). Palladium, copper, and zinc bis(dithiocarbamate) complexes of the same ligands showed similar behavior, but nickel piperazine complexes with 4-phenyl, alkyl, and 3-alkoxy tails are non-mesomorphic (1485). 

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